Wild butt guesses here, but that's how I work on my own stuff. Underneath the switch on the foot pedal that you step on, there is a rubber cap that is supposed to keep water out of the switch. Make sure it's not worn. If it is, it won't depress the actual switch which lies underneath it. The other thing is that the switch you bypassed would melt internally if I used it on 5 (high) for too long. Make sure you have continuity through the switch and that the terminals haven't melted away inside.