1950's Westinghouse Issue

Have a 6-stop 50's era Westinghouse with an MG set. Car is (literally) burning up the Speed Potentiometer after several runs. The MG set was just replaced because it was having issues, but not burning up the potentiometer. I think is most likely related to the MG set being replaced, but not sure where to start.

ERL, REL, DMR????? What are you calling the speed pot? and when you say it burns up after a few runs, Did it run normally? Did it burst into flame after the run? etc. What issues did the generator have? Give us a little information.