Good question....i don't now the definitive answer but i put a little grease in mine just to be on the safe side.
It also pays(for routine maintenance purposes) to cut a slot in that holder so the cable can be removed more easily.
Mine is a staccato rattle and is almost as irritating as the loose baffle in my Honda 1100 ACE Cruiser. It sounds like a jackhammer at high speed or heavy load. Sounds like the rods are about to come out, Embarrassing in the least. I will give the cardboard thing a shot, or maybe a piece of neoprene. Thanx Keith (trackfodder) Williams
I am trying out another approach. The inside of the cover was cleaned with acetone and 1/16 cork sheet gasket material was glued inside with Gorilla glue (polyurethane glue). If that is still noisy I may try the mousepad idea someone suggested on the outside of the cover.
I intend to replace the philips screws with socket head cap screws. Is there anything that can be used in the way of a lock washer that will not dig into the aluminum, or is locktite best?