More information needed…. wood work tool? Portable? Linisher? Metal tool? Make? Photo? Without information we can’t help a lot
. Basic repair is to give it a dose of switch cleaner. Contacts? They can fail due to to an arc forming and the spark creates pimples on the top of the contact. A diamond lap will cut it flat. Neither are good permanent repairs.
Edit…. autotype again!
Edited By Zan on 20/11/2018 20:35:15