Just got a Senco medium crown stapler, I think it’s the SNS45XL or something like that. After three days of moderate use it has failed twice. After a shot it suddenly starts blowing a lot of air through the exhaust and won’t retract the firing pin. Both times I took it apart and put it back together. There are quite a few large O-rings in there and I assume one is somehow coming unseated, but I can’t see that any of them are out of their grooves. Both times I put it back together and it worked–laying on the hands, basically. Should I replace the O-rings and see if this helps, send it back (I’ve got a lot of cedar shingles to staple up so this is not preferred), or what? My older Senco guns have been basically flawless, but this new one is getting off to a bad start.