Any sort of Electrical Contact Cleaner will work to fix the switch. The problem with the switches is dirty contacts. Volkswagen is replacing the switches with new ones with different contact metals trying to find one that doesn't corrode as badly and, thus far, haven't found one.
If you're going to try contact cleaning, don't scrape it physically. That's ridiculous. Use a spray. I recommend Chemtronics ES6100 or any decent contact cleaner. Try alliedelec.com and type "contact cleaner" and you'll find a variety of stuff on there or just google it. Techspray makes some good contact cleaners too. Just get good stuff. Don't use the junk from Radio Shack. I just open up the switch and spray the contacts. It works fine and you can use that stuff on keyboards and anything else electronic you want to clean off. It's really great.
The design of the switch is not flawed as much as the type of metal they're using for their contacts is cheap and inferior. They need to use better contact material and/or (the best solution) use sealed contacts instead of the open-air ones they're using now. Volkswagen feels that it's more economical for them to recall the cars and replace the switches with more inferior ones rather than find a vendor to design a new one that isn't going to corrode. They'd have to find a vendor willing to engineer them a new switch with better contact material. That costs Volkswagen money and there's a formula involved and the cost of the recall is less that the net cost of leaving the flawed products out there.
So just use contact cleaner and if you're not good with tearing open the switch, just replace it every year...it's a cheap part. I don't think VW's going to ever have a decent switch in there.
There's a product called Zerust that's a rust preventative stick on cartridge that lasts 2-years and you can glue it on and it covers a 2-foot radius. It absorbs moisture and it's a really cool thing. I snap one underneath my dash and it keeps the moisture and rust from building up all underneath there. I started doing that in my Volvo 240 because of a corrosion problem in its fusebox and it's worked well for under the dash of the VW at keeping the brake light switch from corroding like the old ones. It might be worth a try. I use a VC2-2 cartridge under the dash of all of my cars to keep all the electrical contacts from rusting and I change it every 2 years.
Modified by bryanmenard at 1:01 PM 12-12-2006