I have 2 railking engines, both brand new, just purchased new, And after 20 minutes run time, just stop running. The front drivers were spinnin and the back ones locked up. I was running at 30 mph scale Talk about emergency stop. Back to MTH they go
On is the Big Boy from the freight set and the other is a cab forward SP.
This is why I love modern diesels. no problemo

Check the hex screws that hold the drivers to the wheels. They have a tendency to work loose and bind up the drivers. Seems that the odds would be against your two engines having the same problem, but thats where I would look first.

Bummer there dude!

My new Imperial Y6b had an issue with the screws that hold the eccentric cranks on the drivers coming loose, and then the crank would rotate causing the mechanism to bind and stop the works. I repositioned each and tightened them up; no problem so far. If they come loose again the trusty blue loctite is standing at the ready!

Rod