[NostalgiaRadioTime]

Others have done far more of these than I and I'm sure can chime in with their own techniques. Bottom line is you're going to have to disconnect a number of wires to separate the sub chassis totally from the main chassis. So the best thing you can do is label each wire you disconnect with a small piece of tape, number them, make a sketch showing each numbered wire to ensure you know where it came from / where it's going. The more detailed your notes / sketches are, the better off you'll be when it comes time to reassemble. Be patient, and don't try rushing through it. Take your time and you'll have success.