I have had the same experience with K-Line Alco's. I added a second motor to the A unit and powered an additional A unit too. Now longer trains are fine. I would suggest that you add a second Pullmor. Or, you may want to choose the Williams powered trucks with can motors. I've done both. Converting a Pullmor truck to a can motor may be problematic, I've not tried that. The easy swap is the integrated truck and motor.