Hey,
I deal with a lot of projector issues with my work. We have roughly 160 Hitachi Short Throws of the ED-A100 and CP-A100 variety.
Unfortunately this has been a common issue, we are into our second year and have already had more than 15 failures on the mirror door motors.
The warranties have been taking care of them, however we have to take them off their mounts every time they fail.
Our failures have been entirely ED-A100's and are a year older than our CP-A100's. Hope this helps.