Welcome to genvibe
This is a not uncommon failure. There are no electrical stops on it, the motor is always pushing. It drives a plastic gear set that moves the air source flap, switching between fresh and recirc reverses the motor, but either way when the flap reaches its mechanical travel limit, the motor is always trying to move it forward. What happens is eventually, a few teeth on one of the gears fail
There are a number of threads on this issue, one that made the maintenance index list (a sticky in the maintenance bay section) is viewtopic.php?t=23692
The gear that gets stripped has a small enough range of rotation that its possible to take the part out, take it apart and reposition the internal gear so that the stripped teeth aren't in the range of travel.
When it failed on mine, I just bought a whole new part