Drive pin will not retract

Check band # 175520 (black rubber band around the outside of the cylinder) is what causes the piston to retract. If the check band is in place, then problem could be caused by cracked lower bumper, worn piston oring or cylinder seal on the headvalve. IF the cylinder seal is bad, air will leak between seal and the top of the cylinder and could push piston down cylinder. If piston oring is too loose, the piston will not stay at the top of the cylinder. If you point the nose of the gun up then down again and the driver moves within the cylinder, replace the oring. Good luck

Porter cable uses a rubber band around the cylinder as check seal to push cylinder up. Pull cylinder and make sure that the band is place around series of holes in cylinder (about center of the cylinder ). If the band is in place then check for too much air leaking out of the nose due to worn/cracked bumper or lower bushing (washer with slot). If bumper and lower washer good, suspect debris in head vent preventing air form excaping or the shaft if the driver is bent (easy to check, driver should be easy to push back up from down position). Good luck

Nail feeder on this gun is both air and spring controlled. Air pressure retracts the feeder and a strong spring pushes the feeder back to front. Remove nails and leave side door open. Dry fire gun very rapidly against thick rubber pad and watch the feeder retract and return. It should move very rapidly all the way back and front again. If it appears to move slower than piston is moving then follow next step. Pull the feeder back manually with tip of screwdriver. It should be very hard to overcome spring. If spring feels strong then suspect feedpiston oring or air supply to feedpiston chamber is restricted with debris from inside of the gun housing or air is leaking where body of gun mates with lower nose. There is a small white oring that seals between body and nose base. Sometimes this oring will be over-compressed thus restricting air flow into feed chamber. Remove two allen screws at front of base to split body from base and reveal this oring. Parts are available at www.toolpartsdirect.com. Good holidays

oil real well

One or more of the rubber o-rings inside the gun are worn or broken. Air is leaking out of where it needs to go to push the driver back up. This is a good gun and worth rebuilding. Unfortunately Hitachi doesn't make rebuild kits for their guns, you have to have a breakdown and order each part you need seperately. If you do this, replace all of the o-rings, if one went bad the others are not far behind. If you take it to a repair shop make sure they repalce all the o-rings.

You have one or more worn o-rings in the head of the gun. They direct the air to the proper parts of the gun to first drive the nail then to return the driver to the top of the gun for the next nail. Depending on the manufacturer and your model number, some companies make kits to replace the o-rings (always replace all of them). For some companies you have to get a breakdown of the gun and order each o-ring seperately.

I believe the drive pin is spring loaded, try oiling the moving parts, maybe inside also, or the air may not be releasing from chamber after actuating, check after lubricating

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.

you need a top end rebuild kit

the fan is what returns the valve in the chamber, whilst it may have been lubed it must be spotless in the chamber. Use paslode gun cleaner a clean cloth and the handle of a wooden spoon or similar and clean all residue and grime out of chamber and re lube. Or you just have a dead tool that was used for parts! good luck