xsb50 help!

My xsb50 is losing air, you can hear the hiss through the loading port or if the bolt is closed you can hear it in the barrel. The valve stem has been replaced on warranty but did not help. I think it could be the oring outside the valve or possibly the valve seat itself. has anyone else experienced this? Any ideas would be appreciated.

[spysir]

It's the valve "stem" (?) part #33.  Who fixed it under warrenty? Xisco seems to only replace he entire rifle or send you the parts, do they fix them now?
John

I CAN shoot  two,

canshooter, the bam50/51's are the most forgiving pcp's ever. You've got to have toes as fingers not to twiddle with a BAM51. So easy. I'm a used to be analytical chemist, but if they told me years ago that airguns were so much fun, I would only weigh pellets all along.
Taking the valve's apart is so much fun. I do it every second week, to try and make another ajustment.
Don't have the details now, but will soon post, what I stole from YKW

If you can hear air escaping down the barrel it is most likely that the striker pin has broken through the plastic valve. Air then escapes through the hole where the pin has ruptured the plastic seal.  Whoever you sent it to to be fixed probably tried to glue it and it didn't work. The whole striker valve seal needs to be replaced.

The striker valve seal can be broken by repeatedly firing onto the pin when the air tank has been overfilled and you experience valve lock. The pin is gradually then hammered through the plastic seal.