S510 power fluctuation

[PiL]

Hi gents, I've not been using the 510 for a while as I noticed the accuracy not up to scratch. I've removed the a/t and changed the seals in the past. It has a tiny air leak but I'm not too bothered about but after chronoing this afternoon power is fluctuating. It was set at 11.4 but now its got (hot). I'm pretty sure it's not just a case of turning it down as I say it's fluctuating, what could the problem be, please?
The gun was manufactured 2007, could the valve face be the cause of the problem?
Steve

[Roger5]

Could be firing valve, breech seal, transfer port seal, but I think I would turn it down a bit first
Small leak, could be fill valve, gauge, gauge mount seals
Fire it with no pellet, see if you can feel any air escaping from either breech seal, on from under bolt Housing

[PiL]

Thanks for the reply Roger5, will do.
This has been my hft rifle in the past and if found to be (hot), would of been suspended, so I've always made sure it was under the limit.

[poguemahone]

sounds like valve extrusion, a chrono string should confirm it

[PiL]

That was my thinking too! I tried to do a proper chrony last weekend but was getting too many errors. In the meantime, I've turned the venturi screw in a tad and will try the chrono again today

Steve