I have a Stuart 10V which is very free running but it appears to be blowing a lot of air straight through to the exhaust pipe. When running I detect the 'pulse' of air at each end of the stroke but there seems to be air running straight through.
what could be be causing this?
The slide valve is centred, with a little free play and exposing the top and bottom port at each end of the stroke. The piston is a good fit in the cylinder.