I think, or I hope that was my suggestion that she could use some of the non slip matting made of rubber that you can buy at most discount stores for your dishes in your cupboard. I have the green stuff but it comes in many colors, white, tan etc. It's super thin, and has holes in it. I also use it on my work bench to hold pieces of wood when I carve wood using a router.
What I did was cut a strip about four inches long and one half inch wide, just enough to wrap around the LNB, then push the LNB into the ring. It was thick enough in some places that the rubber wouldn't insert itself into the ring, and I had to use a very small knife to sort of force the rubber matting into the ring between the ring and the LNB. Is any of this making sense?
Then when I tightened the one screw, just as the LNB started to wobble, I released the pressure of my hand and it just sort of stayed there, so I stopped everything, and it's been holding like that for nearly six months.
Another thing you could try, and this is a better method, but harder to do, take the ring off the arms, and drill a couple of holes offset by 1/3 the distance around the ring, and put two more screws into the holes, THAT will hold the LNB without doing any damage. When I posted that idea to Dee-Ann, I said to look at the way there were three screws holding the light fixture in the bathroom.
Is that / are those the ideas you were referring too?
Hope this helps.
Photto