My brand new hitachi NV45AB2 roofing nailer leaks air through the trigger when it is half depressed. I purchased one and returned it only to find the new one I recieved to replace it does the same thing. Is this a design feature or have I gotten two faulty guns in a row. Everything about the gun operates exceptionaly other than the slight leak.

Leaking under trigger could be the ball seal part # 875645 if leak starts as soon as you connect the air hose. If no air leaks when you connect hose but begins to leak when you depress the trigger then replace the oring on the plunger which is part # 874820. If air leaks when you connect the hose and the ball mentioned above is good then most likely is leaking from oring # 876161 installed on cylinder plate (remove head and pull out the plate). Good luck.

Remove the 3mm roll pin holding the trigger in place and set aside the trigger plunger (white plastic plunger should have an oring on groove). Remove the fitting that holds the trigger plunger and replace vinyl ball #875645 or check for debris under ball. Good luck with your repair.

Replace the trigger

If air is leaking from the trigger, check vinyl ball and oring on the white plastic firing pin. If air seems to leak from the plunger just in front of the trigger (with air connected and nails removed move plunger with finger and listen for change in sound), remove the head and pull out the cylinder. The outer oring to the plate around the cylinder is bad, however, clean the cylinder and lube with white grease. Good luck

Two areas to check when air leaks from around the trigger. Rubber ball under trigger pin will cause air to leak, however when good side of the ball falls on the seat, air will not leak for a while. If air is leaking from plunger pin (just in fromt of the trigger pin), remove the head and pull out the cylinder plate to reveal broken oring (oring part # 876161). Good luck with your repair project.

Could be leaking from trigger or in front of trigger at plunger. Spray soapy water on area and determing exact leak. If from trigger pin, remove pin holding metal trigger (3mm roll pin) and check white plastic plunger for oring on groove. If oring is in place then check vinyl ball inside trigger valve bushing. Replace as needed. If leak is in front of trigger at black boot, remove head and replace oring on outer part of cylinder plate (donut shaped plate at top). Good luck

could be either that or a damaged o ring, when was the last time serviced, all o rings replaced?? could be that the tool needs a thorough cleaning and new one installed. it is not hard

Remove the trigger by removing the roll pin and check that there is an oring installed on the trigger plunger. The plunger is a white plastic part and requires a small oring about 1/4 " in size. You can buy orings at Lowes Lumber in the plumbing department, about one dollar for package of ten. That should take care of leak when trigger is depressed. Good luck and post again if you need more help.

If the driver moves on it's own then it's o-ring is shot,replace it. Pop the feeder cap and clean all the roof crud that's built up underneath it.Now you can see the feeder spring,check to see if broke or old and replace.The feeder plunger is air assisted so hook the air up and depress it, it should depress hard and pop right back up. If not it needs to be cleaned and new o-rings. If this doesn't work then it's a new feeder plate you need. good luck.
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