Track problems -- short circuit?

[Charlie B]

wire the section of the switch that you are no longer using to the siding and see if it heats like before. If it does it is in the switch, The siding was not a problem before because that is where the section of the switch you are now using was originally wired. Actually for a siding you only need one track insulated and a single SPST switch to cut and restore power across the gap.