what does this mean? MM ?

[BrianG]

If you replace the switch, get a closed-frame type. It'll keep the dirt out better, which keeps the contacts cleaner. I never liked slide switches. Here is a decent small one: http://www.radioshack.com/product/in...entPage=search

Before you go out and buy the switch, cut the existing switch off and tie the wires together and solder. Heatshrink them and run it. If the problem goes away, then the answer is obvious.