Since you have that out, I'd soak it in an alcohol bath. Distilled water would work too supposing the switches took a soda bath.
Chances are it might be dried lube from the factory making them stick, and this is where the alcohol will help.
Leave it in for a while and occassionally work the switches.
Once you can work the switches, pull it out and let it dry. Then I'd suggest a spray down with DeOxit.