When tinkering and changing dishes on my motorised system (dishes from 60cm to 1.2m), I've always tightened the clamps to the motor stub as tightly as possible but haven't done the same with the motor clamps. I worked on the theory that if the assembly moves slightly, I could correct the loss of signal by altering the longitude in the receiver settings. After the Winter/Spring storm season, I would set the receiver back to my location and realign the dish. It may not sound like it, but it's better than bending/breaking clamps...