Are the rails nickle? Brass? Do they look oxidized, dull? Or, bright and shiny? I know there are track cleaners so the engines can pick up power from the rails. You may well have one or two among the boxes. The wheels wear off the oxidation as they roll. But, if either the rails or the wheels have oxidation where they make contact, it interrupts/ limits power flow.
A quick search found this one:
http://www.centerline-products.com/rail_wheel.htmAnyway, polish some rails near the transformer connections and maybe some loco wheels.
The motors have a lot of gear reduction. So, the motor can spin the wheels easily. But, wheels have a reeaally hard time spinning the motor. If they do have worm gear drive, unlikely to have the wheels turn the motor.
Looks like a lot of fun with your inheritance.
Cheers,