Right sde turn signal not working

1975 corvette, 80,000 miles, 350ci

The left turn signals work.
I replaced the front and rear bulbs for the right side turn signals. They light up, but still did not blink. I then replaced the flasher unit on the fuse panel. The left side signals work. Strangely enough, the left side worked when the flasher unit was not in. Does the round flasher unit control the turn signals or the emergency flasher system?

Do I have a wiring problem or is it possible the turn signal switch that is located in the steering column have something to do with it?
Mike