I bought a Bachmann Plus F7 second-hand from a Model Rail show here in the UK yesterday. It ran very well on DC so I fitted a Bachmann 36-553 BEMF decoder and it now runs even better. The model uses the chassis as an earth return which I don't like much. So, I removed the sliding pickups on the one side that connect with the chassis and soldered some wires to the pickups so that all pickup connections are now fully wired. Then, when I soldered the decoder wires to the motor, I used insulating tape on the inside of the chassis where the one brush connection is made in dc. I also replaced the light bulb with an LED. There's plenty of room for the decoder so I attached it to the chassis at the rear. The whole conversion took about 2 hours and is a bit fiddly but well worth the effort.