I had the same problem and it was an easy fix. Two small o-rings were worn out. I replaced them and works fine. Had to drive out the two pins in order to get at the trigger valve. Just used a small nail to do so.

Hi, Yes it goes over the holes and is a cylinder check valve for return air. Nail guns use low pressure to pull the piston driver assembly back up to the top of the cylinder and this check valve helps it do that. Hope this helps.

[QUOTE=americantoolman;5093]The piston driver on my tool does not retract like it should when bump firing the tool. While holding the trigger and pressing to wood it fires but hangs up on return. If I fire like a sequential fire tool pulling the trigger each time it fires and retracts like normal.

I just cleaned the tool and replaced all o rings and packings. Changed out cylinder seal and rechecked trigger parts. Now I'm begining to swap out parts - process of elimination. Anybody seen this before? Any ideas? Thanks, Mike." Thanks, mike.

Hi Mike,

I am stumped with your problem as well. I can't figure why the gun would fire OK sequentially but not while bumping. Many issues with nail gun pistons not returning are caused by the trigger valve. You might want to check there for bad o-rings or maybe debris from worn part elsewhere in the gun.

Sorry I can't be more help. Let us know how it turns out.

Good Luck!

-UtahAV
-Mark

Finally figured it out. Simple really. The adjustable screw on the push lever was too far out, eventhough it was just short of the valve bushing it would not allow the plunger to move out enough to fully cycle the tool. I guess the push lever was out of play while firing sequentually.

Good to hear that it was nothing serious. I hadn't though of that. Makes sense though.

Thanks for letting us all know what the solution was!

-UtahAV
-Mark

Hey AntV,
aside from taking it back apart and reassembling a few times..:) try holding down the trigger with the safety engaged.[no nails and pressing down on some wood]and then hook the air back up..this is an old repair trick from the factory techs..also make sure your o-rings are lubed of course..
hope this helps...
Craig