Update.
I picked up a multimeter in order to test the wiring. It seems I have a ground fault somewhere between the headlight bucket connector and the connector under the seat. (Resistance reading between frame and purple/green wire) This also includes the rear brake switch. I disconnected the wiring from the rear brake switch (seemed a little corroded) and reattached. The fuse didn't blow right away. Went for a short test ride and it blew within about 10 minutes. On the right track but still haven't found the problem.
ps. The location of the rear brake switch is a real PITA. Although I was able to disconnect the wires it is not easy with large hands. It looks like I will need to remove the rear tire and fender in order to access it.
