First time restorer working on a poor little Lionel 736. Got new fingers and installation went fine. Tested e-unit separately and it cycled well. I bench tested the motor prior and it worked well too. After putting it all back in the chassis, I connected leads to the pickup and frame all I got was the e-unit cycling and a hum. Nothing from the motor.
After many hours and triple checking my connections and the finger contacts, I broke out the multi tester and discovered that the factory green ground wire connection on the fingers was no good. A touch of solder at that connection and reassembly it now runs like a top.
It’s amazing the you could put the same e-unit back together In 5 minutes or an hour. Touchy little things.