1992 Marathon won't go

[WallySmith]

Solenoid clicks, but cart won't go. Replaced batteries, replaced solenoid, replaced forward reverse switch, replaced the controller with an AllTrax 400 series 36 volt. Need help. I used the circuit diagram that came with the new speed controller to hook it up. The old controller had 4 lugs, the new one has 3. The wire that went to the forth lug on the old controller shows to connect to the reversing switch on the drawing that came with the new controller. The varistor is not shone on the new drawing. Any help with this will be appreciated. I think I need an expert. This all started as an erratic problem, sometimes it would go and some times just click.