Control card is at the very rear of the lift, behind the rectangular plate with the Crown logo on it. Search google for 'Flight Systems EV100' and you should turn up some info on the control system and testing procedures. Try disconnecting the battery and then unseating and reseating the connectors into the control card. Check potentiometer voltage at the control card. There is a large capacitor in the back which will give you a nasty belt if you touch the terminals, even with the battery disconnected so take care.