I'm new to HO ... bought several HO used pieces ... I have 12 Locos and about 1/2 of them stutter ... I'm testing them on a short piece of track; forward then backward ... they are all Bachman Locos ... I have 4 Santa Fe 307s (1 runs great both ways, 1 stutters both ways, the other 2 stutter in reverse) ... I have a UP 824 (stutters in reverse) ... and I have 6 others that all run well - Santa Fe 307, 3500, 6067 and UP 866, 1206 (2) and Chessie system 7071 ... any help would be appreciated ...