The knob that tightens the sleeve on the shaft of my Terrova trolling motor is stripped (picture attached). Has anyone else had this problem and found a replacement knob that has a more durable design? I can't get the sleeve tight enough to support the motor so the shaft is all the way down and makes it impossible to use in shallow water. Pressing a plastic knob on the steel threaded shaft doesn't seem like the best design. Granted, I probably cranked it a bit more than I needed to, but now that its stripped, its pretty much non functioning.