Hi Folks, newbie, '79 CM400 w/ puzzling turn signal issue.

Hello everyone, Western NY here, cold & wet most of the time, so barn find bikes abound! I found a cute '79 Honda CM400 for my daughter. Budget constraints meant that I could only afford a fixer-uper. It's a '79 CM400 with 11K on the spedo. It was missing the seat, tail lights and rear signals, so I replaced those things with aftermarket. After a lot of other work, (leaky carbs, petcock, etc...) I got the bike to fire up. The left hand turn signals function fine but when I turn the switch to the right it causes the flasher unit to buzz like an angry bumble bee. The RH signal lights do not flash. I have checked the bulbs, switching them from right to left and it still acts the same way. I am inexperienced with electrical issues and really need some help to get this ready for my daughter's upcomming birthday. Any help or advice is appreciated!