Rex models HO and writes:

“I just put a new Walthers Mainline F7B unit with a Sound Value Diesel Walthers Mainline Decoder on the track. It works fine going forward. In reverse at slow speeds, it will lose power (no sound) and stop but, in most cases, immediately start up again. This can happen 2 or 3 times while moving 12 inches. It does not stop while running at mid-range speeds and higher. Nothing changed after cleaning the track. I tried jiggling the wires but could not find a cause and effect. Usually, I don’t have time to reach the engine. Any ideas?”