First, take it by the head and pull. (Make sure you get the whole spinal cord)
Second, find a cool 70's diagram on how to wire a chopper...
Consult the shop manual... (What the fuck?!?)
Pitch the extra crap (safety switches, warning lights, whatever the law doesn't require, etc) and hope for the best...of course they changed a whole bunch of colours and shit from the 500 to the 550, and I have a random assortment of bits from both.