On one of my sidings I have a Kadee magnetic uncoupler ramp (plate) which mounts between the rails.It has been there for a number of years and I have never had any problem with it.Today, for the first time, I had occasion to back my BLI Mikado over the ramp to pick up a car.As soon as the rear truck of the tender is over the ramp the engine loses power.When I nudge it a 1/2 inch or so…it will resume running.IT has no effect on the front truck or the engine when they pass over, nor does it seem to have a problem escaping the siding when pulling foward. Any suggestions? It does’nt happen with any other engines with or without a speaker in the tender.
Sounds like to me you have a loose connection in the rail.
Just a thought.
Make sure the uncoupling magnet is straight and centered between the rails, and that the tender wheels are not riding up onto it and losing contact with the rail. The second thing to check is to make sure the coupler glad hand (the hose) is not too low and lifting the tender off of the rail as it passes over the magnet. The magnet may be crooked or too high.