Tungsten would be better. But then you would need a much better motor with a lot of torque to get it rolling. Here is an update, I tested 74 F units had 66 good and 8 bad. So far that was all the locomotives that were awaiting decoders in the F series. Of the 8, 6 were my favorite DRGW scheme, 2 F7's and 4 B Units and a pair of NP B units. That takes care of all the DC locomotives awaiting decoders. Next up is pulling the remaining decodered units and testing them. The box is getting heavier with all the bad locomotives. In the end, it might be cheaper to put them all in the car and drive them to Longmont CO.