You're sure it isn't the hammer oring, and that it doesn't need oil? There are some field techs who... well... shouldn't be.
Otherwise, if you're trying to remove the puncture cup, a long, fat screwdriver will do it.
Try pushing the valve pin by hand, or by tool. If the pin doesn't give way at all, then it's an issue there. Also, check the face of the pin valve to see if it's still round with one flat section. Recocking requires that flat section to be sufficiently open during the shot. If the pin has mushroomed at all, it may be causing trouble.
Otherwise, if the gun is firing up to chrono speed on the first shot without a recock, it's more likely the hammer. I have a hard time believing the valve itself has an issue.
Oh, last thing: try backing your velocity all the way out before test-firing. This will save you some air and may help fix the issue.
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