I don't know how model train repair can survive as a trade. A "simple" repair that takes only two hours to diagnose, disassemble, find parts, test, reassemble and do a final look-over, billed at a relatively measly 40 bucks an hour (this kind of skilled labor really should be billed out at way more if you're trying to support a business) is 80 bucks in labor.
Then let's figure it was a replacement of a drive shaft. So there's 30 bucks in parts after markups.
Add in 25 bucks shipping each way makes a "simple" repair a whopping 160 bucks. Although collectors with 1500 dollar engines may find that acceptable to keep their prize piece running, the vast majority of people with a problem will say "I only paid 300 for that engine, no way I'm putting another 160 into it. Screw it, it's junk"
And then they move on to something else.
The future of train repairs is going to be individuals who have learned on their own and are willing to charge way-below market rates to help people continue to enjoy the hobby. And they're not going to do that for just any Schmo who calls.
Which is why I'd like @gunrunnerjohn and @GGG to forward me their address so I can send them a greeting card and a bottle of nice bourbon as a bribe to stay on their good side for when I need help in the future.