Sliding shoes work best with postwar Lionel tubular switches, crossings and accessories. Other brands can damage or snag the sliding shoes.
There is a flat bronze spring that sits on top of the rivet that provides the downward pressure on the sliding shoe. On those with the wire soldered into the the rivet there is a two contact spring. Make sure those springs are adjusted so the push the shoe straight down. If out of adjustment they can force one end of the shoe farther down that it is design for. This can cause the shoes to snag.
