And you say you have checked it for visual damage, there is no lube anywhere on the poppit except the oring (and only a small small amount) and there is no crap in the hole in the side of the poppit?
And you've tried resetting the poppit by screwing the back cap all the way in, so the poppit seals itself properly, and you then wound it back out to the correct velocity?
You've checked all orings on the bolt, bolt guide and poppit for visual damage?
Well next question is settings. Whats your input and board settings please? I assume you have the stock board?