New Precision Craft Model E7 Running Poorly

[Herc Driver]

Finally figured it out...and here's the answer.

I found the plastic hex nut on the rear drive shaft was stripped just enough that it didn't keep good contact with the motor drum. During my initial testing, when I lifted the rear truck from the tracks with the front trucks supplying the electrical power from the tracks to the motor, the rear wheels spun since the motor drum could generate just enough contact to spin the hex nut on the drive shaft. So I wrongly thought, "since the wheels turn - it must be ok."

But today when I took the engine all apart and slowly spun the motor by hand, I noticed the rear truck gearing wasn't turning. I disassembled the engine further and saw the rear hex nut had rounded-off corners. No wonder it wouldn't run smoothly and lurched around the track.

So a tiny touch of CA glue (since I didn't know what else to use) made a solid contact between the plastic hex nut and the motor drum, and this E7 cruises along the rails without hesitation and at all speeds. I might open it back up and replace the 'bad" hex nut with a good one from my parts stock (it's easy to break the bond of CA glue if you put the parts in the freezer for about 10 minutes)...but that's for a another day.

What did I learn from all of this? When in doubt and there's no obvious answer, take it apart and look at each individual part. Had I done that before, I would have realized the part was bad and solved this two days ago.

But I also learned the value of friendship between a LHS owner and repeat customer. As a "reward" for solving this problem, my LHS owner gave the engine to me and my boys as a "payment" for fixing it for him. So we ended up with a nice pre-Christmas present!