The old Right-Of-Way power supply used a pair of Variacs (autotransformers) taking 110V on the input and running the outputs through a pair of 120-to-24VAC step-down transformers. The original price on that unit was around $400 as I recall, which was less than I could build it for.
MRC makes a "Pure Sine Wave" AC transformer. We have a couple at P&P powering the visitor-operated loops. In all probability, they're using variacs to feed step-down transformers.
All that said, it sounds like you might have a current-draw/leak problem. One of the things you want to check with the Pullmor motors is for carbon build-up between the armature plates. This is from the carbon brushes and dust building up. Because it's conductive actually shorts the brushes with a resistive load and will cause a voltage drop. You can clean that out with a toothpick. You should also spray them with contact cleaner. Also make sure your track connections are solid and you have sufficient feed drops.
Hope this helps.
