Thanks for all info.
If I can find a piece of scrap copper flashing, I think I am going to try to make a small, shallow, copper box to fit over the center plastic square dead spot, run a hot insulated wire up through the rivet hole in the center of the crossing, strip a small bit of insulation off of the top of the wire, solder it to the underside of the box, and then epoxy the box down. I see no reason why this wouldn't supply center rail power to the rollers as the engine passes over the center of the crossing.
If I am able to do this, I will report back on the results. If it doesn't work, I guess I will try to build tethers.
Thanks
Mannyrock