Dome satellite antenna acting weird

[RV Vagabond]

I am parked with no satellite blockages at all, but my Winegard in-motion dome antenna keeps vibrating and shaking the dish and making that space ship noise. I took the plastic dome off and everything looks normal. It will quiet down for a new minutes then start the shaking and noise again. Anybody know why this keeps happening?

[chindog]

Mine sometimes does that for up to a half hour, but if I just leave it alone, it finally quits.

[deandec]

Ours will do that while searching for signal. Even after obtaining a signal.

I guess it is looking for perfection?