front brake switch question

[Admiral Crunch]

Ever since I bought my bike 18 months ago, I've had a little issue with the front brake switch.  When I bought the bike, the front brake didn't make the brake light come on, and I traced it to the switch under the brake lever.  I popped the switch open and cleaned the contact that closes when you apply the brake.  I scraped a discolored film off the contacts, and they were nice and shiny again. I put it back on the bike, and all was well.  I've had to repeat this process three more times since I bought the bike.  Is there any reason the contact should be corroding/gunking up like this?  There is nothing obviously wrong with the switch like holes or cracks that would let in moisture.  Is there something wrong, or is this just the way they are?

[sledge]

Switch contacts can have a very thin conductive coating applied to them that cuts down arcing when they open and close and it prolongs the lifespan of the switch. My guess is that the contacts are arcing and getting pitting because the coating has now all gone...........get a new switch, they cost next to nothing.