[digital_blue]

Originally Posted by Darklen

Dummy me, now that I've reread the original post, does the piston head even have vent holes? I know TM does not and I always drill them in whenever I open a TM box. There is usually 4 knockout pin marks on the head face I use as a guide for the first four holes, then I measure and drill another four holes in between these for eight holes spaced equally running just inside the outer rim of the piston head.

SYN outlined the proper procedure for testing compression, though since this box is a Well, I'd probably just replace the oring with a quality part, slightly larger, that doesn't have a seam around it. If you don't have that option, try getting an oring lube that will expand the orings, like DOW 55. This can help the sealing factor quite a bit, but it could also destroy the oring as I have no idea what orings Well use.

Without doing the compression test, like SYN outlined, the piston head will appear quite loose in the cylinder. It had to be loose on the return or pulling stroke as the motor is already fighting the spring and you want as much air in the cylinder as possible before it hits the compression stage.

The piston head is not vented. I actually took off the O-ring and put it down the cylinder and there seems to be a lot of play. Should there be this much spacing between the O-ring and the cylinder?