I made this replacement for my wife to use on the Jon boat. It works good.
I will make one for my big boat when my pedal quits. I know the aggravation you are experiencing.
You don't have to get this fancy with the wiring. You see I have the left/right buttons on one foot and on/off for the other. Speed and continuous are in the box and easy to reach.
It is about 50 bucks for the parts (minus Allan's yeller cables). Actually lots cheaper than a new foot control.
http://i188.photobucket.com/albums/z..._1292Small.jpg
http://i188.photobucket.com/albums/z..._1293Small.jpg