I've got an '84 Champion' Merc 150, next to my control box I've got a stainless steel plate screwed to the sidewall. I can't figure out what it goes to - (writing has been worn off). There's a knob in the center of the plate that has a variable adjustment to it - (just like a volume control on a stereo). When I removed it I found that the knob was attached to a small circuit board & attached to that were three wires, ORANGE, BROWN & BLACK. Can you help? It also needs replacing - do you have any ideas on who would carry an item like this? THANKS FOR HELPING