[Dave at Pelican Parts]

I'm not sure how you would absolutely confirm the MC as the source of your troubles, but it sounds likely. You might try bleeding the system to see if the pedal comes back that way--but then the question is how did air get in?

The solution to the one-pole switch is to not plug the brown wire in and to tape it out of the way. The two-pole switch grounds through the brown wire, while the one-pole switch grounds through its threads.

--DD