Yeah I took the foot apart and that's how I found the black stuff. After further investigation I learned I was only getting 15 volts at the trolling motor. I have a battery that is only putting out 4 volts so my onboard charger lied to me. I hooked up another battery and put the foot back together and it works great now. Thank goodness.
Oh don't worry. I have one ordered. Lol. Not risking it again.