Originally Posted by Thetis
Make sure the screws meet the flat part of the shaft. If they don't you will face the described problem unless motor B is dead. I had twice this problem with motor B before going BL.
I think they are in the "flat" (it's more a hole, than flat) At first I thought it screwed into it, but never tightened. What I think might be happening is that the plastic has stripped, and the screw backs out with vibration. Think I need a new Lower Rotor Spindle. I tried "Lock Tight" on the screw, but that didn't help.