Today I returned three Digitrax DH123D decoders that I had bought in January from the Hobby Smith in Portland. After installing them into new engines, I had recently purchased, they would not retain their long address. I coded their long address using my Digitrax Zephyr, unsuccessfully tried to run them and then found that they had changed to a completely different address. Happily (sort of) I was able to take them back to Hobby Smith for a refund. I will now be looking into identifying a more reliable decoder.