I have two ovals on my layout and changing from one to another is facilitated by two sets of two Peco Insulfrog points back to back with isolating rail joiners between them . Each oval is powered separately from an analogue Gaugemaster series TS controller which has three separate outlets and control knobs. The polarity and direction on each oval is the same. Steam outline locos pass over from the outer to the inner oval no problem but diesels stall because of the long wheelbase and pickups on separate bogies? Is this because of the isolating joiners not being spaced etc.? Apologies for ignorance but every attempt to read up online or in a book gets too complicated for me to understand.