I changed the feeder springs in my hitachi NV83 a2 and it wants to double fire and jaming up the driver with seconded nail. it was skip nailing before i changed springs. any help you could give me would be greatly appreciated

NV50 nailer is very difficult to repair due to complicated feeder /feeder spring / feeder retainer pin design. You most likely need to replace the orings on the feeder piston. Problem is that you must remove the feed pin/ spring to get the piston out. If you are going to attempt to replace the orings, study how the pin is installed otherwise you will make it worse. Order new springs (2 different springs ) and install them when you are going back together. Good luck

The allen screw/s that you mention are there to plug holes where automatic equipment would normally connect (such as automatic nailing machines) . This is only a plug and should not be driven in too far. I have also seen allen screws installed in the head to repair small crack/s.

If the nail will not advance, easy test will determine problem. Open door and remove the nails. Lightly tap the nose of the gun against coiled rubber hose or soft wood with door open. If the driver falls to bottom, the piston oring needs to be replaced. The driver should stay at top of cylinder. Next pull back the feeder to rear position and check for tension. The feeder should spring back towards you when you push. Finally, the check paws on the door should return to extended positon when you push on them. Replace springs as needed. Connect air to gun and rapidly bump fire the gun against rubber. The feeder should move back and forward just as quickly as the driver moves. Good luck

Hitachi coil roofing nailer will skip nails if the piston oring is worn, the feed spring is weak or lower bumper is cracked. Easy to check. Remove nails and air supply. With side door open point nose of gun up then down again. If the piston moves up and down in the cylinder, replace the piston oring. If piston does not move and is in the up position, check the feed spring for tension. With air supply removed and door open, slide feeder back and press on feeder from door side to check tension. It should spring back to position against rails.If is feels loose, replace spring and retainer pin if the pin is worn. If piston oring is good, and the feeder has good spring tension, suspect lower bumper and the plastic part below the bumper called the "sheet". Remove head and pull the cylinder to examine lower bumper. Parts are available at www.toolpartsdirect.com. Good luck with your repair

Hitachi coil roofing nailer will skip nails if the piston oring is worn, the feed spring is weak or lower bumper is cracked. Easy to check. Remove nails and air supply. With side door open point nose of gun up then down again. If the piston moves up and down in the cylinder, replace the piston oring. If piston does not move and is in the up position, check the feed spring for tension. With air supply removed and door open, slide feeder back and press on feeder from door side to check tension. It should spring back to position against rails.If is feels loose, replace spring and retainer pin if the pin is worn. If piston oring is good, and the feeder has good spring tension, suspect lower bumper and the plastic part below the bumper called the "sheet". Remove head and pull the cylinder to examine lower bumper. Parts are available at www.toolpartsdirect.com. Good luck with your repair

Make sure that orings are in good shape, lower bumper not cracked, (no leaks and the driver/piston stays at the top position, if piston drops a little or all the way down with no nails in gun, replace piston oring). Also check spring tension for feeder and two check paws in the door (feeder tension should be firm ). Adjust the timing screw up or down one or two turns and test (timing screw at the top of safety foot, head of screw pushes on the firing valve ). Test for lower bumper cracked. Remove nails and leave side door open. Hold the nose of the gun against coiled air hose or thick rubber and press and hold the trigger. The piston will stay down against the bumper until you release the trigger. No air should leak out the driver path. If air leaks past driver suspect bad bumper. Test action of feeder piston. Remove side cover to feed piston and clean debris. With air disconnected, move the feed piston back and forward. There should be a little resistance, if it moves very easy, suspect orings worn. As soon as you connect the air line. the feed piston should move forward with force, note the position of the feeder. Now with air disconnected, place nails on the feeder. The first nail should be well within the path of the driver. If not fully under driver path suspect worn feeder / feeder retainer pin, or debris inside feed piston chamber preventing piston from full forward travel (debris from inside of the gun will enter the feed piston chamber usually broken bits of lower bumper). Replace parts as needed. Good luck with your repair.

Usually due to bent driver, worn driver oring or lower bumper cracked, weak or broken feeder spring. Remove head being careful not to tear gasket. Pull the driver and check for bend in shaft or chipped end. If the end of the driver is chipped or rounded, grind tip flat (remove as little as possible ). Piston should hold position in the cylinder and drop down under its own weight. Examine lower bumper. If missing pieces, replace with new. Lube orings with silicone paste (sold at Lowes in plumbing department). Also check for correct nails. Should be 15 degree metal wire. There is an older hitachi nailer with a metal canister (nv50aa) that uses plastic strip nails. These nails are too close together to work properly in the #nv65 gun and will usually shoot two nails. Good luck

This is a very popular gun, very light and powerful. Skipping nails is not a common problem. Here are a few things to check that would cause the issue. (First remove air hose and nails.) Worn piston oring (piston will be in the down position). Open side door and check that piston is at top. If oring ok, check feed spring under feeder claw. If spring is in place, push feeder in manually. It should be very difficult to move feeder shaft. If it moves easily then spring inside feeder chamber is broken. If ok, connect air to gun, leaving side door open (nails removed) and bump fire gun against hard rubber (or coiled rubber hose ) very rapidly. While bump firing rapidly, look at feeder moving back and forward. It should be moving very quickly keeping up with speed of driver. If it appears to be moving slowly compared to driver there is an air feed restriction to feeder chamber. Check for debris in small air passage to chamber. Remove two allen screws holding nose of gun to body and examine the small white teflon oring between nose and body(part #149885). Sometimes this oring traps dirt and grime or just simply gets pressed so tightly that center hole is restricted. You must use the correct teflon oring here because the nose and body fit so tightly together that a rubber oring will close air path. Good luck.

Your nailer shares design features with Milwaukee and Ridgid. All three brands experience the same issue. Lets go thru a series of simple tests to determine the problem. First and most simple test, manually load the nails and fire the gun untill miss-fire. Upon mis-fire disconnect air, open latch and check if the driver is all the way up into the cylinder or is partially down blocking next nail. If driver is down blocking next nail, replace the driver oring and retest. If driver is up all the way, remove nails, reconnect airline, leave latch open and fire gun against rubber (old tire or coiled up waterhose/airhose) this time holding the gun down and keeping the trigger depressed. In this position, the driver will remain down and feeder will remain retracted. With feeder retracted and screwdriver in hand carefully check the spring tension on the feeder (should be rather firm tension on spring and the feeder must retract with good force). If no tension or weak, replace feed spring. When you finally release the trigger, the driver will retract and the feeder should return with good force. If feeder does not return with force, replace orings and spring behind feed piston. If all tests are ok, remove head, check lower bumper in gun for cracks or missing pieces. Replace as necessary. Lube all orings with silicone lube available at Lowes in the plumbing department. (Danco brand) Good luck on your repair and email your questions.

Yes there are many different kinds of siding nails from all over the world. Stores that sell nails buy/import nails from where-ever the labor/cost is cheapest. The importer uses a private label so the nails from one company in China will produced according to requirements and will be sold under many different brands in the US. The result is that the nails are not exactly the same from batch to batch. I have seen coils that measure from 3/16 to 1/4 inch between the nails. Closer to 1/4 inch is more ideal for your nailer. The (nv65ah) is listed as a 16 degree canister angle, however you probably purchased 15 degree nails because nothing else is available. Should be no problem assuming everything is working ok. When you insert nails into feeder, make sure that the first nailhead is positioned under the driver and not too far to the edge because the driver will bend the nail if not hitting dead center to the nail shaft. Ask for a sample section/ roll of different brands and type of nail to find the best nail for your gun. Best place to find nails is a fastener company that only sell nails/ nailers/compressors to contractors. For best results, make sure that the driver is squared/flat at the tip. If is not, remove the driver and grind it flat (do not grind too much). If driver and nails check out ok, then it may be time to replace springs/orings in feeder area. Go to www.toolpartsdirect.com and take a look at the breakdown of your gun and notice that there are several springs in the feeder area that will weaken over time/use. There should be two springs in doorlatch area, one on the feeder itself, and one large spring pushing on the feed piston. Good luck with your issue and email if you have question.