How to tune up a Bachmann (or AHM) GP18 and other diesels by Mehano

They may be cheap, but these Mehano-made GP18s sold by Bachmann and AHM can be some very smooth and reliable runners! The same mechanism (or at least very similar ones) has been used in many diesels from AHM, IHC, Bachmann, Life-Like, Model Power, Mantua, and others along the way for about 50 years now, and I've found them to be dependable and easy to work on. In fact, I've only ever had one dud, and the rest have always been great!