Thanks to the advice given here, CN9000 is smokin' up a storm! . . .
In fact, it'll positively drive you from the room with smoke set to anything other than low! I ordered a new smoke unit from Lionel rather than try to replace the motor on the balky unit.
Why? It was the path of least resistance! The Lionel web site made it very easy to order a new unit and have it shipped to Canada for a nominal ten dollar postage fee. Getting a package of five MTH motors was not simple as their website seems strictly a US thing with no provision for shipping to Canada. Wish they would fix that!
Just as well as, I could not figure out how to remove and replace just the motor from the unit. Can't see how it is affixed to the unit? Just yank the impeller off to find mounting screws? Not sure. Impeller didn't seem to want to come off.
But it's smokin' like a champ with the new unit! If the photo looks blurry, well the engine was stationary in the shot with the revs up a tad. A few seconds later you might not have been able to see the engine at all! 
