Arfa,

Thanks for the informative reply. I have yet to
disassemble anything. I was hoping it would fix itself, or that I
would be able to figure out how to use the oven by tweaking the dials
in a certain way, but it is just getting worse, actually, so I will be
opening it up soon.
The switch on my oven in a bit different, of course, but, like
yours, it is a rotary mechanical, so possibly can be cleaned, of
course. I don't know if it is attached with screws, or rivets.
I will need to walk the oven out from the wall, get the front
panel off, then see what's there. It will be a weekend project, I
think.