And it's goodnight from me after another fruitless night of attempts to get this MTH loco to take it's long address. Tried all sorts of ways to do it, even while running it along my 6' of track @ speed step 2. Weird thing is that when I press enter to set it, the horn toots 3 times, which normally would indicate acceptance by the decoder, but it doesn't matter if I turn off the power according to instructions, either after or before exiting OPS mode, or not. Just will not "take" the new address.
A thought just then, I wonder if it's because I have 2 of these with the same cab #. I plan to always run them as a pair facing the same way, seeing there appears to be no chance of consisting them with other decoders or even with themselves (I've made inquiries here to see if any MTH dealers have the decoder "reflashing" service available, but none do, don't even service them), so I figured that giving them both the same long address, they should (maybe not) respond to commands in unison. The other one was used and came already set and always responds to it's long address.