If I'm reading this right, the turn signal relay gets power from the positive terminal of the battery and sends it to the switch. The switch then sends it to either the right or the left turn signal bulbs. Still not clear to me where a short would have to be in this circuit to constantly turn on the right turn signal.  It looks to me like if the blue wire in your diagram is shorted to the green or black wire leading to the right turn signal, then the right signals would flash continuously. Is that right?Sorry, it's also been more than 30 years since I read any circuit diagrams.

Thanks, I'll check it out. I suspect it's under one of the tank supports, near the signal relay. That would be easy!