Either go to DCC or get a higher current rated power contoller.Make sure you keep the voltage at 12 volts but the current is what you need .The controller you have is probably rated at .75 or 1 amp,going to 1.5 or 2 amp will give the motor the power it needs.The motor will only take the current it needs to perform properly if it is available,if it's not available it will struggle and get warm to hot.

Thanks Hunt, will give that a try. I'm using an Intellibox II for programming.

How do I dim the headlight on a Heisler loco. I can't see any reference to headlight dimming on the program sheet.....Peter

It's an easy fix Peter, worth while rebuilding the trucks you remove for later, just in case you can't get the parts in the future. .....  .....Peter

Hello Peter, I replaced the gear drives on my five Shays years ago with the replacement program in 2013 and all are still operating well, they get plenty of use on my layout. I recently replaced a drive system for a friend who ordered the parts from Bachmann, they appeared to be the same drives as the replacement program drives with the bulkier gears. I prefer to replace the complete truck because some times the clips holding the drive shafts can pop out............Peter