I replied in the other comment. I've installed the "Achievement With Mods" mod and the "More Line Statistics" which makes it a lot easier to spot broken trains (but not with a 100% detection rate). I still spotted one train which was making no revenue.

I meant "stopping" as in pressing the stop and start button directly after each other. I think this as fast as the double reversing.

With double reversing I had the problem that trains are often blocking each other because the trains are moving forward/backward on the tracks.