. . .

your rare earth magnet placement is wrong.  I have done it and it works fine. magnets below the rail, do not put it in centre line of track.

Ahhhhh

So offset it one side or the other.

Not really...

See this thread:

https://forum.mrhmag.com/post/simple-and-easy-use-of-permanent-magnet-for-kadee-uncoupling-without-unwanted-uncoupling-12208230

One thing that may help is the suggestion in the above thread on how to make the magnetic field visible using a bottle, steel wool, and mineral oil. 

Compare the magnetic field of a MT or KATO track magnet with the placement of your rare earth magnets. Move them around until  you get a similar field.

Gotta love Science!

Not really ???

Sorry but I do not understand this reply above.

The rare earth magnets must be offset to different sides so it pulls the kadee's trip pins to the side for un-coupling.  It requires two magnets.

Having the magnet in center line creates a pull on the trip pin for each magnet it passes over. this to me was a no no and not a solution. Even if using the modified Kadee under-track magnets.  The Kadee has  another bad side effect when turned 90 degrees, it pushes the trip pin upwards along with pulling it downwards twice for each pass over.

Marc

Offset...

The comment to "offset the magnet to one side OR the other" (emphasis added) implies using ONE magnet, under ONE rail. As shown in Marc's sketch, you want TWO magnets, one under EACH rail.

This is why I suggested using the method described in the other thread to visualize the magnetic field.

Thanks that makes sense..

With regards to physics the magnets to either side of the rail makes sense, Will try and inform,,, thanks,

Update

So I have tried two different magnets. One I purchased the other is from the read write heads of a hard drive. The one I purchased seem to be a bust. However the hard drive magnets when two are laid perpendicular to and under the track I get excellent results. All of your suggestions helped a ton. As I suspected it appears to be the manner in which the flux field is around the magnets themselves that cause the pin to deflect in the proper direction.
I will continue experimenting with the purchased magnets as I bought a bunch of them.
Thanks for all the input.