2003 Malibu Heat door motor

Had been intermittent for about a year and now doesn't work at all. I removed it without difficulty after removing glove compartment. I expected to find one of the plastic gears cracked or broken, but all of them were in good shape and moved freely. The heat door moves very easily by hand and the control knob on the dash seems to be OK. I guess the problem must be the electronics in the module, but the mechanics I spoke with said they have never heard of this - the problem always was a cracked plastic gear. Since the module is expensive and can't be returned, I rather not buy one unless it is actually the problem. Has anyone had a similar problem?

Does the actuator work as you dial different settings when it's not connected to the blend door shaft? A blend door actuator should not be that expensive.

Joel