JGL, It's possible a tiny drop of lightweight oil on the smoke motor shaft will help the squealing. I am not familiar with that smoke unit, but there have been a couple of threads/videos of folks having success with that method. Might be worth a try before replacement?
Many of the smoke unit motors seem to be fairly similar. I have replaced a Lionel Legacy smoke motor with an MTH smoke motor and they were pretty much the same motor as far as I could tell. Worked fine and it's still working after 3 years or so.