I am powering several Marx 1590 switches with dc on my Lionel layout and am using an RC circuit to guard against switch solenoid burnout.  I also have put in non-derailing capability just as one does for Lionel 1121 switches. All works well except that on some of the switches, the locomotive stalls out.  Is this due to an interaction between the 16V dc and the ac driving the train?   It's getting pretty complicated, what with the protection circuitry and the two kinds of voltage source.  Clearly, I'm in over my head.  Help!