I spoke with the owner (Andy?) about a electric forklift with what I thought had a problem with the Curtis motor speed controller. It's not a true forklift, but rather a Power Stacker, a walk-behind made by Clark, the CSP 15. He told me that since it would move at all that the probelm was NOT the controller, but rather one of the potentiometers in the handle.
So I opened the cover to the handle and found a small circuit board. The forward/reverse controls are run by this circuit board. When you rotate the handle there was a round black plastic disc connected to the handle that was in turn connected to the circuit board. The disc had a magnet and a slot. I found a small magnet that was loose inside the circuit board compartment. That magnet had fallen out of the slot located on the disc. When I replaced the magnet, (which operates the potentiometer) the controls started working properly.
Thank you VERY much. I had been looking for a controller on eBay for almost a year, and that wasn't even what I needed. I had purchased the Power Stacker on eBay for around $450.00. It's in excellent condition. And now it WORKS! Best regards, Steve Spevak, Winchester, VA.