Were Do I Find A Variable Wiper Switch ???

When and if you find out please let me know. I have the 3 speed variable in my 68 cuda that is missing a speed. Awhile back I was trying to see if a switch from a different application would work but I didn't find any joy. I'm too scared to try and take mine apart to see if I could clean a contact or rebuild it in any way cause I'd probably bread something and then I'd have nothing.