Does it have a rubber boot over it? Some do, and you can remove the boot, and get access to the bits underneath…one being the plunger, the other the screw.
Once you get it out, you may even be able to use something simple and clean it up. They’re pretty simple devices…mostly a contact to ground, a single wire and a spring. Use some sort of spray. I personally hate WD-40, but that’s me.
Chase