You can get advice when you take a picture of the open locomotive from all sides so we can see what could have been?

Screenshot 2023-12-04 at 12.25.09 PM.png (1,641kb) downloaded 20 time(s).Thanks guys - my name is Justin by the way, and it's a 3-rail track with 3-rail trains.

I think you're on to something - I removed the middle slider and put the engine back on the track and while it obviously didn't run, the other engine did in fact run (telling me the middle slider is at least one culprit here). I also ran a continuity test using my multimeter testing both middle rail to wheel (when the middle rail was mounted) and it beeped, telling me that's not good news.

I'm attaching pictures of the inside of the engine and the slider. While I see the slider looks the same as the original pictures you posted (minus the fact that it appears to have a separate screw hole for some reason), I'm not sure how this thing would EVER have run like this. To do a final test, I actually slid a piece of paper under the slider on the contact side that WASN'T supposed to touch the metal PCB connector and when I put it on the track, while the engine didn't run, it didn't prevent the other engine on the track from running (no short), so I think that further points to the slider (unless that paper simply stopped the positive voltage from touching the engine, but that the contact plate/slider simply aren't touching or something else is going wrong).

Now, the question is - why. I'm wondering if there is a piece of insulation missing from under the slider and/or if the contact of the slider isn't aligning to that gold connection plate for some reason (or entirely the wrong slider)? Thoughts/ideas?

Screenshot 2023-12-04 at 12.10.24 PM.png (1,985kb) downloaded 26 time(s). Screenshot 2023-12-04 at 12.10.47 PM.png (2,203kb) downloaded 18 time(s). Screenshot 2023-12-04 at 12.10.31 PM.png (3,001kb) downloaded 20 time(s). Screenshot 2023-12-04 at 12.10.36 PM.png (3,333kb) downloaded 18 time(s). Screenshot 2023-12-04 at 12.10.41 PM.png (3,559kb) downloaded 20 time(s).

I don't own a BR81 but I think the body is metal and I know the chassis is metal. You have a lot of wires and connection points on the right side of the engine. If any should touch the metal shell, it will short out. I have had this happen with an early BR38 and I resolved the issue by placing a piece of electrical tape on the inside of the body opposite the soldered electrical connections and my problem was solved.

Hi Justin
The slider is the modern equivalent of the old one. The old one had just a longer Pertinax piece (the brown insulator piece) to fit onto metal positioning tabs.
I believe your slider was just positionned the wrong way.
It is NOT symetrical so one position is good and rotating by half a turn, it is bad.
Good or Bad?
On your picture we clearly see the slider orientation is bad because the the two contact tongues, instead of touching the contact PCB will touch the frame making a short circuit

Nothing is missing in your loco I think
Cheers
Jean

hello jekhokie !!
Yes thats a good idea.If thats not bringing any resoults,you have to check the shifter reley (umschalter) in the lokomotive.This loko has telexcouplings so that complicates things a bit.
Its spesially the contacts you must check on the top of the reley.Be shure that nothing are in contact with mass.Careful they are very fragile.If this is ok,you scould have to move further to the engine.

Good luck ! kaav800