Just out of curiosity why do you need to replace the switch? If it's missing that's a no brainer, but if it's due to operation of the switch I feel the need to mention that it is a "Center" off type swith. In other words, when you rock it forward it is on Hi, and when you rock it back it is on Low. The only time it is off is when it is in the center position.
I only bring this up because many of us here found that out the hard way. Who reads instructions before riding a Bike anyway? In fact one of our NW members has a favorite tale about how his wife would not quit complaining about how hot the seat was on one of their first summer rides. He told her it was off, only to find out later that it was in the High position!
Just in case,
John