Who is schooled in "Grease"? (Need some tough stuff)

I wonder if something like this UHMW (slippery plastic) tape applied to the sides of the extruded block the shoes slide in would help solve the clacking problem? I guess the real question would be what exactly is causing the shoes to come together strongly enough to clack. Apparently they're sticking somehow, and the sides of this block seem to be the most likely place to me, but I suppose it could also be the edges of the tongue piece that slides between the shoes or something else as well.