I have a Stanley bostich bt200 18 gauge brad mail gun.
I had a bad nail jab a few years ago and ever since it leaks air out the exhaust in the handle.
I could deal with it as I use the gun very little but now so much air leaks out, my compressor can't keep up and just runs when I have it connected.
I've opened up the main cylinder housing and taken out the trigger valve and all the o rings are intact. For the amount of air that comes out one of the o rings would have to missing or not fitting in it slot right. Its not a little hiss but more like what you would get out of an air gun. Only one part looks out of place and its called the diaphram head valve.
I found the rebuild kit for it but its from 50 to 60 dollars. I think I only spent $80 on it 12 years ago and a new one is only $89. If I can't point to a simple part to replace I may just go to Harbor Freight and get their el cheapo one for $18. It would work better than the one I have now.
Not sure what to do. This is a tool a use rarely.