I have an 88 TA with an electronic heater/AC control. The motor that moves the hot/cold divider ( forgive me for not knowing the proper parts descriptions) in the heater box needs replacing. Its very slow when it works and sometimes stops halfway when you slide the hot/cold **** to hot or cold. When you unhook the rod from the motor to the door it moves freely and doesn't hang up at all so its a tired motor. Is it possible to rebuild these, or just replace? What is the actual part name and where can I buy one to replace? Thanks