I have a machine that has that same kind of friction wheel. One of the Needlebar guys that has one like mine told me to take some sandpaper to it....run the motor while holding the sandpaper against the rubber....unfortunately, it was too late for that...the spousal unit had already torn the rubber piece getting it off the "post".
Off to the hardware store, where he found a rubber piece to replace it!
Whatever it was originally for, it fit perfectly, and now the machine just has the wonderful "shuttle song" instead of the "Thumper song".