I have a 1999 Motorguide Tracker Series 30 trolling motor which has a 37 lb thrust. On our last fishing trip, my son-in-law ssid that the trolling motor just started going where it wanted to. The motor was still operating but foot control was not operating. Some one told me it could be a pin sheared (but I figured that a shear pin would keep prop from turning. One guy told me it could be a keyway broken. Then another told me that perhaps a wire had come loose from the foot control or maybe a bad resistor. Can anyone help me with this one please? Thanks in advance!