I was just re-reading some of this thread and noticed that Gene was having engine troubles here too. See the new thread on "one-way loco". I can't help but wonder, Gene, with all your different types of track mixed together, if you just somehow haven't created one of those electrical gremlins that rear up and bite you from time to time, like Doug's traveling short.
As for your comment about Kato engines not liking small radii, not true. I have run Katos through 6-1/2" radii on a store layout with no problem. One I built for the hobby shop where I worked in Phoenix.
It all boils down to what Mike and I have been trying to tell you. Slow down. The most important part of layout building is the trackwork. After all, your trains must negotiate this ribbon of nickel-silver over and over and over again. Believe it or not, model trains work on the exact same principle as the 1:1 trains do. A "steel wheel on a steel track, with a very small contact area providing the friction necessary to develop adhesion and therefore pulling power". Prototype trains have a weight to tonnage pulled ratio. So do model trains. Prototype trains do not like bumps, large gaps, bends, kinks out of gauge rail or loose rail. Guess what. Same for model trains. It is the same principle in a smaller scale.
Now go back and look at your track. Get your eye right down on the rail and look along it. Is it a relatively flat ribbon or a wavy undulating snake? I did notice in your pictures that the track was not centered in the AMI roadbed at one point, but took a different curve than the roadbed itself. If you have laid out the AMI carefully and to your scaled centerline, the track should follow this same course. Right? This is again another thing I do not like about the AMI. It is very hard to reposition the track once you think you have it down. On cork, you can adjust it until it is right and then you tack it in place. You test run it, find the trouble spots, readjust by pulling a nail or two, retack, retest and finally ballast it down. AMI is not that forgiving.
What all this boils down to is that you need to spend the most time on your layout actually laying the track. If you don't have perfect track work, no matter how well the layout is secnicked or lit, or how good your buildings are, if the trains will not run, no fun.
B-)