Need guidance in getting my dad's trains to work.....Marx post war O gage (1953 +/-). The transformer seems sluggish and is not original to the set. Does anyone know what would be the best approach to getting this running again. When activated it "hums" but doesn't move. Is the trans possibly too weak? I have had it running in the past but bought some new (used) tracks for my great grandson, and his mom and dad are trying to get it running again. Oh well, it's fun to set it up and push it around the track, but it sure would be nice if I could advise them on how to get it running properly again. I'm not nearby to see what's up so I'm trying to do this by process of elimination, over the phone. Any helpful ideas would be appreciated.