The battery voltage sounds fairly good. The place to check the voltage is at the terminals to the motor windlass. If the volts stay OK (>11.0) then it's the motor. If the voltage drops at the motor but not at the batteries then it's the wiring or switch. Your symptoms sound like my Maxwell as the motor was dying but prior to that I also had problems with the foot switch a couple of years earlier. You might try your local auto electric shop for repairs. We have one in Portland that is pretty good at working on Off the Wall stuff. Maybe there is one in your area.