I received two of these beautiful moguls last week and the whistles are just fantasic! Thank you Lionel. But, when run both were wobbly and jerky, Everett #11 much more than Lakawanna #565. So much so that the bell swung wildly when running.
I have refrained from commenting until I have been able to do some in depth investigation using information from this terrific thread!
The problem was more pronounced at lower speeds. I observed my ammeter on my Lionel ZW-L transformer and yes there was an increase of amperage with every jerk, from 1.9 to 2.1 amps (I had a few lighted passengers cars on at the time, not just the locomotive). Not a fatal amount but not right. And, every jerk occurred in cadence with every rotation of the drivers, I could tell by listening to the chugging while watching the ammeter. Could not detect ANY binding in the running gear. I changed the traction tires to a 'thinner in thickness but wider in width' tread (MTH Mikado spares) with general improvement in bumpiness but the rotational jerk was still there, so much so that at startup the engine at times would stall with "1 blinking light", which I would then reset.
I popped the shell off, placed the chassis on the track and gently turned the motor flywheel with my fingers, remembering that earlier on in this thread someone mentioned that the play in the first set of drivers seemed excessive. THERE WAS WITH EVERY ROTATION OF THE DRIVE WHEELS AN EASILY DETECTABLE BINDING OF THE RUNNING GEAR, AT THE SAME POSITION EVERY TIME. Upon close inspection with a dental pick I found that the main rod segment between the middle driver and the first driver on the fireman's side would bind. I suppose at low speeds this is enough to jerk or stall the engine, and higher speeds possibly the locomotive can just roll through this point with the additional momentum.
By the way, my conventional moguls from a previous release a few years back have very little play in those drivers, much closer tolerances between the drive rod and the shoulder of the pin holding it to the driver, it looks to me.
Rick