First impression is that the switch is a special that is screened for minimum hum and noise pick up. Can you see any way to remove the metal can around the switch to allow access to the contacts, or is the whole thing one piece?
It's a fairly 'normal' Japanese style slider switch - almost certainly a custom one made for that model - it's not particularly 'screened', the metal is simply part of the switch, and what holds it all together.
It's easy to squirt a little WD40 in there, no need to remove anything.