That pin just keeps the bakelite from spinning inside the outer steel casing. You won't get any access from removing it.
I cleaned mine by removing the rubber cover from the button and dowsed the opening around the button with carb cleaner, aired it out with a compressor, then used contact cleaner, followed by a final blow out. Once you start using the solenoid, they tend to be self cleaning. The little spark from each engagement burns off any accumulated dirt. The worst thing for a contact is to let it sit for years, so the brass and copper corrodes over...but even then, if you can get it to engage it will start to clean itself off. What kills the contacts is when a combustible, like oil, gets inside and fries the surfaces of the contacts.