It’s not the center rollers, it’s the ground through the wheel sets. Does this have the plastic base under the truck block? If so, measure the resistance from the opposite sides of the wheel sets and from truck to truck. If high resistance, either the 2/3 rail switch is bad, or you have bad continuity between the axle bearings and truck block.
Remove the pickups, plastic base and wheel sets and get some 0.005” brass shim material and make a “U” shaped cradle to reduce the clearance on the bronze wheel bearings. Common fix we did at MTH.
If it is the die cast truck block, that is a bit more complicated…
