Let me preface by saying this is just conjecture based on my experience, and the only way to know for sure would be to have a tech knowledgable in LionChief engines take a look...
That said, it sounds like there is something binding up in the drive train. The electronics in a LC+ engine will try to maintain speed, and they adjust the speed by very quickly (hundreds of times per second) turning the motor on and off. Normally the motor freely spins between pulses of power, coasting along at low speeds with very little power applied. If the motor is jammed up, However, the electronics would have to apply a lot of power to get the motor turning, then when it switches off would sense the motor slowing, much quicker than it should, and slam on the power again. In essence you'd have an effect similar to driving a car with the parking brake set. Full throttle to get moving and jerking to a stop when you let off the gas. With this happening many times every second it translates into a shaking of the engine... and excessive ware on the motor and electronics.
I would start by checking that the gear-box was reassembled correctly and that the motor can spin freely. With the shell off, observe the motor for vibration and jerkiness with the drivetrain fully assembled, then test again with the motor removed from the truck to see if it moves smoothly. You could have a bent shaft on the motor, or some other problem in the truck that is binding things up.
JGL
Hi John,
Thank you for taking to the time to describe what looks like my exact situation. Now my concern is now that I've test ran it for 1 hour in each direction, FWD/RVS, I was potentially doing damage to all the parts involved; if that's the case, I think I will return it and get a new one. I would take it apart, but since it's new and I'm new at this hobby, my concern is that I'll do more harm than good, and if I do harm, then I'm out of luck in terms of a return / warranty service.
I thinking maybe mine was used? I ordered it NIB, but why I say that is because it has nicks on top of the cab cab, and the gears were already greased (outside, to the side of the wheels) I know MTH and other LC's don't come pre-greased on the outside gears next to the wheelset, so I was a little thrown off by that. I sent Lionel a email yesterday asking them does it come pre-greased.
Thanks again John, I really appreciate your description of what just could be the issue I'm having with it. Now that's 4 issues in row on all new items This LC+ , and ....
2. Lionel B unit that arc on the center rail sent power over the coupler (tape fixes that -- please see attachments)
3. MTH Christmas Locomotive that intermittently also does the same on the electro-coupler and smells like ozone in the front cab (and now the whole basement) when in reverse pulling a single car consist,
4. Another MTH Locomotive that I haven't tried yet because I was first working on the MTH Locomotive, but that issue is cosmetic so far, with the railings having been popped out and scratched, haven't ran it on the track yet.