Hi Ted
i will be ordering 4 of the frog inserts as I only have 4 #6 switches. Today I did some work on one switch as a test bed for all four of them. I milled .030 off the inside lower web of both guard rails and milled each end at 10degrees to make a nice ramp on each end. I was going to mention exactly what you stated, the gauge of the swing rails is too narrow in places. I removed both and did more sanding of the swing rail aces in the needed areas and worked on the ends so now the wheelsno longer ride up on the rails. I will post pictures later.