As for the metal lathe I used, if you stick to P&D replacement parts you can do everything with just hand tools. I wanted to change the sprocket ratio for slower speed running. That helped when I used non-back EMF decoders. These days the motor control in the Loksound L is so good I won't change any more drives. The original drive ratio also produces less chain noise.
Because acetyl shrinks over time, there have been outbreaks of cracked gears in many vendor's products, even in certain runs of HO locomotives. Over many years stuff happens.
Question for Pete - Which Tang Band speaker did you fit in your GP9 and where did you install it?
