Cut the lead going to the chassis. I am not familiar with the loco. Take your multimeter and put it on the resistance scale. Check each motor contact with one probe on the chassis. There should be no resistance showing.
Connect all the decoder wires according to the NMRA color code.
Do not add a Bachmann decoder. Get a Digitrax or NCE good quality decoder. The Bachmann decoders are low end Lenz.
I would use a Digitrax DZ125 decoder. NCE has some good up to date decoders as does a couple other manufacturers. I just happen to use some of the 125's. About $19.95 each.
Check with Litchfield Station as they do answer email and usually have good suggestions and service.
I buy most of my DCC stuff from them.
http://www.litchfieldstation.com/DCC-University/index.htm
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I have an Rivarossi Heisler 2 truck that I would like to convert to DCC. I purchased it around 2002, pre DCC. It is not DCC ready, i.e. no plug. I would like to add a Bachmann decoder chip, but not sure how to do it. I have added chips to some standard diesels without any problem, so I know the basics. I have taken the Heisler apart but don't really understand the electrical pick-up. One side of the motor appears to be powered thru the frame. Can I just cut this lead or do I have to do something more involved to isolate the motor?