I have an older, bought in 2006, Motor Guide Freshwater Series trolling motor with 82# of thrust. It doesn't seem to eat to work now and I am not very mechanical. The prop will turn in a slooow jerky manner like it has power and then it doesn't. I haven't used it very much in the past two years due to travel and illness but now I am able to fish and I need it to work. Any ideas short of a new unit?