Maybe I am not describing things correctly. The raised ring (shoulder?) that is supposed to sit in the plate hole and prevent the screw from touching the plate is too wide (not too tall).
Yeah, that was what I thought, but I guess it isn't clear which part of it is too wide. Is the inside or the outside edge of the ring/shoulder too wide?
If the inside is the problem (meaning the diameter of the raised ring is too narrow for the RCA jacks), then wrap some fine grit sandpaper around a pencil or marker and widen the hole from the inside.
If the outside is the problem (meaning the shoulder won't fit into the hole), then you have two options: (a) widen the hole in the metal chassis to fit your new, wider washer, or (b) file the outside of the shoulder ring (not the bottom, and not the outside of the washer itself) to make it thinner. I would do this by sliding the washer onto a tapered marker until it is firmly supported, then use a fingernail emery board to file down the width of the shoulder ring.
