I think I have finally solved most of my TMCC problems. It seems that setting the engine's ID did not always work. I am wondering if the signal strength varies with orientation of the remote. And what about the signal strength sent to the outside rails?
Yesterday, I tried my #777 ommodore Vanderbilt Hudson with TMCC for the first time. I found its ID to be one (the usual default) and was able to change the ID to 77. It seemed everything worked except for the real coupler. BTW, it has a terrific whistle!
Thanks to all who sent suggestions!