Mine did the same last week. Bought touring919's switch from the bike he's parting out. Harness was pretty simple. For a match other than the 919, I guess you'd be looking for something with a single lamp headlight and 7/8th bars.
I was going to go to Ron Ayers site and do the "Where is this part used?" option but the site is down. If it comes back up you can go find the part number for the 919 switch and put it into that section. It will tell you if any other bikes use that switch.
"Towards the end of the vid, it looks like she may have had a bafflectomy." - MarylandMike
Mine did that when i first bought my bike years ago.....i got a new one on warranty....but while i was waiting for it to be ordered, i took it apart and all it was, was a screw had come loose inside...i fixed it but i still got a new one fitted under warranty!!
unfortunately you have to replace it with the right kind of turn signal... not only does that switch the turn signal duties, it also handles cutting the power to the front turn signal running lights on the proper side.
Its probably something pretty simple inside that broke / came loose. I have always found that if a little plastic part breaks, some 5 minute epoxy and 1 layer of fiberglass does the trick.