I have two twin Athren SD75 M locos I purchased a little over a year ago at the OKC train show and have ran them very little. I got them out the other day when I got back into the train mode and one of them runs like a champ and the other runs well but very slow, (about 25% of what the first one runs) I have cleaned the tracks and wheels well and made no difference, Right now they are DC running on a DCC layout, (Digitrax Super Chief). Any suggestions as to what the problem might be, maybe in the pickups or something? When it is running it is very smooth and no flickering light or anything. Any suggestions? Thanks, Mike