If it were mine, I would first try a spritz of contact cleaner into
the switch via the front panel slot (IIR465C). All contact
cleaners are the same - mineral oil and alcohol - so the cheapest
Radio Shack stuff works as well as anything. WD40 also works well.
==============================
On various occsasions I have been told that WD40 is NOT the right cleaning
agent for electrical systems involving plastic insulation re wiring, etc. I
always use (non chlorinated) contact cleaner as available from Rat Shack and
similar stores.
Here in the UK I use contact cleaner supplied by Maplin.

Frank GM0CSZ / KN6WH