I'll give you the spin on that. After I got my first one, and modified it to a 'conventional' cab instead of the west coast cab, and got it to run as a critical layout locomotive, I realized that keeping it running over a time would be a chore. I already have a policy of having a 'spare' locomotive for critical layout functions.
I got extra wheels, gears, contacts, everything I could from Atlas before 'that guy' bought out everything and put it on Ebay. Then I picked up a second run Shay before the price went nuts, modified the cast body to match mine, and resold just the body for a profit almost enough to pay for the second locomotive, intact, kept the mechanism.
That's my insurance policy. These things are super finicky, and if they are a 'critical' locomotive for operations, sooner or later they will fail. So picking up an extra mech just to keep the first one running isn't as dumb as you might think.
