Auto derail problem with z1000

My guess is that the isolated rail segment that the auto derail prevention depends on is no longer isolated from the rails on either side of the isolated rail segment. As you are familiar with, when a truck enters the isolated area, the truck wheels/axle short the isolated segment to ground, causing the switch to throw.

See attached pic.    I just don’t see it 

Anyone  see what I am missing    It used to work fine 

I’ve seen a few cases where the two legs of the frog on Ross switches have contact.  Could be contact between the rails or could be one of the staples (spikes) that are causing contact.  Jam a small screwdriver between the rails to separate them and/or jam a piece of heat shrink tape between them or look closely to see if it’s a staple that’s touching both rails.

The two wires being the same color concerns me - out and thru should be different colors and the rail to switch machine wire should match the color of the controller button for out and thru.

That notwithstanding, assuming it is wired correctly, perhaps the wire insulation melted a little from soldering and they are finally touching. Separate them with a small flat screwdriver in the hole.

Does the throw bar move freely or has that started to rub on something? I cannot see it in the photo - check the spring if using a DZ machine

The short rail sections at the frog can touch.  I placed a small piece of styrene between the two pieces of track. 

LEHIGH 74   YOU ARE MY HERO...you and Mike CT had it....little spike wedged in between the 2 rails i got out....10 second fix ....of course after an hour of me rewiring and trouble shooting

thanks again.

I'm not a hero.  Just doing my job.  Troubleshooting can be frustrating, but it's nice when it's any easy fix.