It's too bad you don't have another set so you could try a different controller and see if it still acts the same way. I think if it was me I would go ahead and buy another set, they're only $40, just to figure out what the problem is. I'd offer to send you one of my sets, but postage there and back would be more than half the cost of a new set anyway. Are you planning on building any other trucks in the future? If you are, it might be worth it to buy a new set now just so you have a fresh controller to try out.