There are insulator strips at the bottom of those switches. If they breakdown, the bottom switch
blade will be touching the chasis.
I'm sure that would cause all kinds of problems!
* I would insert some plastic or paper under that bottom switch blade to see if that is a problem.
** Not sure you checked that. If you did, just disregard that suggestion.
*** I also have a Mata Hari...... not sure when I will get to work on it.
John