1225 Polar Express lion chief locomotive

I run this on a seasonal layout with the old tubular track.  I have two "new" 022 switches which are vastly inferior to my postwar versions.  The "frog" is high and makes trains jump when going over them.  Slight adjustments with a hammer not withstanding!  My 1225 had a wire pulled from beneath the trailing truck when going over one of these switches and I can't see where it was originally connected.  I thought it went to the copper brushes to the axles, however I don't see a solder location.  Can't find any videos with good views of the area or repair manuals.  Help!