[John Bartley]

Just as a supplement to Ron's answer :

The capacitor can that you illustrate in your picture is probably both C19 and C20 in one can, so replacing both of them is a good idea.

Ron is correct about the lubricant. To get your lubricating/penetrating fluid into the control more easily, heat the threaded body (the collar) of the switch with a big soldering gun or use a heat gun with a nose cone to focus the heat. The lubricant will penetrate more easily and completely and the switch should free up properly.