NO THEY ARE NOT INTERCHANGEABLE! The problem is this, Many of the thread guides come from older machines, and the screws will not fit the smaller holes on the featherweight or the 301 or several others. The screws are out there, the last time I wanted some I took my featherweight to the store and had him screw some screws in to the hole till we found a few that would fit. Don't force the screw as it will ruin the hole for the feed dog cover plate for the buttonhole or darning plate.The red felt is a spool pin felt, and it might help protect the finish of the bed, but I have never done it. I own about 20 vintage machines, all Singer, and when I have sold them I have always been careful to make sure that the screws all fit.
