When I arrived home last evening I thought a session with my Fluke Multimeter was in order. The 2 spots or areas I mentioned are on the ends of 2 switches with isolated frogs. Adjacent to the frogs are 4" (or so) common rails. The meter told me that the 4" rails leading to the frog are also isolated. That leaves me with about 5 1/2" of no common to the wheels. The jerky I mentioned is probably losing the voltage and picking it back up in that very brief sub-second it takes to reestablish power. With the smoke unit on, the jerky symptom would probably be most visible as more current is being affected by the brief outage.
If it was the hot rail I could do something with the pick-up rollers. Since it is the common rail, I would think the thing to do is solder a common wire to the 4" sections? That should leave the frogs insulated for anti-derail with my DZ-2500 switch machines. Does this sound like the sound solution? I'm open to other thoughts.
