staple gun driver not retracting question

[The Cobbler]

I'll start by saying I like to do a lot of my tool repairs myself, if I can figure out whats wrong.
I have a craftsman POC 1/2" 20 gauge stapler that I bought at a clearance joint along with a bunch of staples. used it several times & the driver broke . My guy that I use to fix stuff told me to toss it that it wasn't worth repairing. I kinda agree with him.
It sat in pcs for more than a year , I found a driver on ebay and ordered it.
put it all back together and now the driver doesn't retract . if I manually push it back up it drives stapes as it should. just wont retract.
I went back to my repair guy and he looked at it, said to leave it with him.
He looked it over , re assembled it and said to me it's not worth investing time into it. his experience is that the farther you get into them the more you find wrong and he just says it's not worth his time ( or mine)
I respect him and I never feel like he's taken advantage of me when he does repair stuff. He said there's an o ring somewhere that needs replacing.

any ideas what to look for?
I don't have it here but if it helps I could take some pics. sorry , don't have the model number either, I was hoping someone could point me to what oring might be bad

 

[cheechi]

spring not connected to anything or weak spring. just because it's 'springy' doesn't mean it's a strong enough spring to retract the driver after the force is exerted.

 

[The Cobbler]

thanks, there is no spring , all pneumatic . should have mentioned it was air

 

[jetdawg]

There is a leak somewhere that is preventing the driver from fully retracting. If you can find an oring kit buy because parts for that thing become obsolete quick. We've tried repairing them but mostly work on senco, hitachi and bostitch because there's a lot of support for these professional guns.

 

[The Cobbler]

..... mostly work on senco, hitachi and bostitch because there's a lot of support for these professional guns.

I agree, I have mostly hitachi, bostitch, paslode. I was just hoping for an easy cheap fix for the odd time I use this one.

BTW, I agree with your sig line