Nope it's not the switch. I will bet that the TM is not a 5 speed, but a variable speed. If that is the case than you have a MOSFET burned out in the motor itself, and now for the very bad news. If this is the case you can only replace the motor head itself with the digial one, they don't make parts for the old one any more. Depending on the size of your motor, one will cost around 380.00. Good luck