your going to have to play with it. make sure its lined up and try and get the piston to center properly.
Also this is the electric forum you would do better asking in the Nitro, or general forum as you would get way more advice.
General Forum
http://www.rcuniverse.com/forum/forumid_179/tt.htm
Nitro Stadium truck forum
http://www.rcuniverse.com/forum/foru...smode_1/tt.htm