Best thing you can do is by an inexpensive multimeter and check the voltage output of the transformer/s you are using. The 750 is a good unit. If you track is clean, your pick up rollers are clean, and the loco is lubricated, Yout MTH locos should fire up. Likewise, the Lionel transformer will also run the MTH engines, but not all the accessories in them. Also make sure you have power going completely to all of your track.
Any transformer needs to put out at least 10 Volts AC to move most older engines. You will need at least that much voltage. The lights will operate on 4 volts and up. So just a head light on is not an indication of the correct power going through the track.... Check all your connections, and get back to us'..
