I didn't want to spend 200 bucks for a mode control motor, but I wanted to have defrosters this winter. I took the motor itself apart. There are 3 little crimped ears that hold the the motor housing onto the gear box. I pulled the housing off and found one of the brushes wasn't hitting the commutator. Put a little more tension in the spring (bent it) now she works like a charm. YeeHaww!

 

Good info, for those of us that like to "tinker". Very unusual for a brush to pop out of its holder like that though...What was the approximate spring pressure, and how big is the brush (at the commutator)?

 

I ahve fixed one in the past as well. The little brush is very small and the whole thing works like a windshield wiper electrical mechanism that puts the wipers down after you turn the switch off in the car. In my case though the brush was actually ever slightly off the contact piece off copper. I simply bent the brush about 2 MM and it is working to this day.

 

The brushes are about the size of a match head. Spring pressure is very light, it just needs to make contact. It's not a coil spring, it looks a little like an open safety pin with a brush on it.