The gun will fire but the plunger will not retract back up into the chamber.

plunger is eiyher nicked or bent. check for any small nicks that might be on the plunger, if so carefully file the nick so it is smooth with the rest of the plunger

You should be able to find parts for your model nailer doing a simple web search. Take out the allen screws on the back of gun, remove the back, inside the chamber you'll find a round metal disc, this is the plunger, the drive pin is attached to the other side, the plunger, and pin is one piece, when you remove it you'll see where the pin has broke off.

To find the model number, look on ebay for hitachi framers and hopefully you will find one listed that looks like yours. If no joy, take the gun to your local fastener/nailgun dealer for parts. The dealer most likely has box full of used parts for your gun. I have seen many older nailers with bent safety foot that caused the plunger to stick in the engaged position. Some nailers have the safety return spring incorporated within the trigger plunger /valve area and still others that have the spring hidden under a guard on one side of the nailer (guard part # 883493). Look under the main body of the nailer for an indention where one side of the safety spring fits into (less than 1/2 inch in diameter) ; directly below the indention will be a point on the safety foot to catch the other side of the spring. Good luck

You have a obstruction in the path of the plunger taake it apart and clean it.

I had this same problem. Well, actually after I modded it. I hope you are good with your hands, because this takes effort.

Unscrew the casing and open the gun (remember to take the battery pack out and have the two plates together so that the wire connecting them doesn't break).

When you see the plating covering the plunger (spring) system take it off, it has about 5 screws.

Since this is extrememly hard to explain in words, look at an internet picture of the internal plunger system. The way it works is that when the spring/tube goes forward (as the motor operates) the 'plunder' (the white thing) stays back. As the orange tube goes forward it triggers and release mechanism that fires the plunger forward due to spring pressure, compressing the air, therefore firing the bullet.

All you have to do (which is what I did) is insert a clip (with the plates open), make sure the jam door is closed, and put the battery pack in (to complete the circuit). Do a bunch of test runs to make sure the white plunger is shooting forward as the mechanism operates.

This will all make sense once you activate the gun without base plates.

Email me at [email protected] if you complete it, have questions and/or comments.

I hope it helped!

PS- while you're at it, you might as well look for online instructions on how to mod the air restrictor (as I am too lazy to write a few more paragraphs!).

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

sometimes mine won't shoot, and i find a single staple in the track, almost ready to fire out , but can't , they can be hard to see in the tract, i keep sharp pliers on hand to clear them. hope this helps

The tool needs to be completely torn down, cleaned out, two orings inside need replaced, re-lubed and re-assembled. takes a technician about 1 hour to do it right. I believe either the orings or dirt is your problem. If blade doesn't return its probably the orings.

you need a top end rebuild kit

The hammer could just need to be oiled or you could have blown a seal in the gun which is not expensive to fix around 20.00 . A lot of times when my gun jams on a nail it gets stuck so the hammer won't go down. I just use something thin that will fit on the hammer and take a hammer and just tap it back into place.