Recently having trouble with RPMs settling down to idle and plugs being rich and am suspicious things are sticking so I ordered an SU tool kit from Moss. I followed the centering jet instructions by using the centering pin in place of the needle. I backed off the jet as far as it would go and slackened off the lock nut. The centering pin fit into the bearing and the piston moved up and down freely. But every time I tightened the lock nut the centering pin would ride up and when the lock nut was tight the piston wouldn't move. I did this multiple times with the same result. After loosening the lock nut the centering pin would then bottom out again and the piston would move freely. Not sure if I'm doing some thing wrong here or if there is a trick involved using this kit. Instructions are minimal.