[K7Sparky]

Is your band switch shaft brass or plated steel?

I expect you are trying to penetrate corrosion - shaft to mounting collar / sleeve and not frozen detente between the chassis and wafers

Keep the chassis oriented so the different penetrating snake oils you try run away from the wafers. By their compounding, penetrates wick so they will travel up a vertical shaft in time. If you can get a bit of wick like a pipe cleaner around the shaft before the wafers it would also be good and change it out as necessary.

Life is better without snake oil on the wafers.

I would use an old syringe and needle (Insulin type is too fine and clog - try your vet, Pet Meds or local Coop) to add the oil just above the sleeve inside the chassis. Spray covers too much territory.

If the shaft is brass, one of the carburetor cleaners might be something to try. The dip type not the spray type. The spray evaporates quickly and you need something to penetrate.

The AFT mentioned by David is an excellent attempt

I also like Kano brand Sili Kroil, Tri Flow and Breakfree among others

A couple of times a day try using a 4" Cresent or make yourself a wider spanner to fit the shaft over the flat. Just a few light wiggles both ways. A soldering iron for some heat on the shaft in front of the mounting sleeve threads after a week or so along with the gentle wiggling might also help.

It took it a long time to corrode so take plenty of time freeing it up. Haste makes broken.