If it's having "trouble" going right, vs not going right at all, I'd first be looking for a mechanical issue with the trolly, bent rails, broken wheels, etc.. Next would be connections and/or broken wires in the trolly harness, then possibly a bad switch in the joystick.
Greyhound used solid state relays to drive the motors, if there was a board/relay issue, you usually get no movement in one, or more, directions. Solid state relays generally work or don't.
Greyhound specific parts are not readily available new, but there's little to worry about. The circuit boards use common parts. The trolly motors rarely fail, and claw coils are available from most distrib's.
D