how to mend honda ex650 generator?

Hi- I have a Honda ex650 suitcase generator.On the side there are the two connectors for the 12v dc feed. The connectors have two plastic thumbwheels which you use to tighten the wires into the two groutlets. One of the plastic thumbwheels has disintegrated and need replacing. The new thumbwheel has arrived and it looks like the whole generator has to come apart to fit it. Can you help explain how to fit it? Thanks.