I'm on my 2nd replacement switch assembly on my '81 R65 .
You can try a cleaner, I'd stay away from contact cleaner, it used to be detrimental to certain types of plastic materials .
You can try something like alcohol to get things cleaned up, but my experience has been, the plastic parts in the switch have worn .
The switch is not 'user friendly', to take apart .
If you do decide to attempt to disassemble it, do so inside a large clear plastic bag, to contain the parts that may try to escape and be forever lost .
