N80 Framing Nailer
These are made from a stronger aluminum than the newer N80s.
They do use the old TVA1 trigger valve, would probably need replacing $10 to $20 on eBay.
Parts and rebuild kits are still available for these nailers, generic and Bostitch factory kits.
N80 Bostitch kits include ORK11 and a shop kit RBK8.
These include the O-rings, cap gasket and cylinder seal.
The bottom piston bumper is a 2 part bumper, the factory kit number is BK3.
I can supply an O-ring kit for these at $12 delivered, but will not include O-rings for the trigger.
This trigger TVA1 (Green Cartridge) has a silicone seal that breaks from age.
These are not available in the trigger rebuild kits seen on ebay, they only have the O-rings.
The best option for a trigger leak is replacing the whole trigger cartridge.
The TVA6 is interchangeable with the factory supplied TVA1.
And the generics are as good as the Bostitch brand, But i would remove the cartridge from the gun and compare them before buying.
The TVA1 has a cap on the end, but not all of the generics do and if you get one without this cap, the trigger will leak between the cartridge and the housing.
Trouble shooting the N80
Trigger leaks / Replace the whole trigger cartridge, generic with cap on bottom, Check your’s first.
Exhaust leak / Moderate leaks, hissing, top end O-ring replacement should fix it.
Exhaust leak / Blowing air, Head valve N80337 replacement (these don’t ship with the O-rings needed) i would try the O-ring replacement first.
Exhaust leak / Cylinder seal # N70155 cracked or missing, it sets on top of the cylinder.
Blowing air from the bottom / Could be the cylinder seal above and a very worn driver O-ring.
Blowing air from the bottom / These guns have a rubber check valve near the base of the cylinder, there will be holes underneath it.