Turn signal failure only on one side

Before 1978 the Malibu was marketed as a Chevelle even though the car came with Malibu emblems. Starting in 1978 Chevrolet dropped the Chevelle name and marketed the car under the Malibu name only. Many believe the Chevelle line ended in 1972 but the 1973-1977 line of Malibu's were still listed in Chevrolet sales literature as Chevelle's (see attached image of original sales brochure. The Malibu emblem can be seen on the bottom right of the grill).
I have traced the wiring to the fuse box. Even though the bulbs on the right light, they just don't flash on and off. Power is coming through the correct wire from the fuse box banana clip in accordance with the Chevy wiring diagram for that year/model obtained from an original Fisher Body Service Manual in my possession.
The bulbs on the left flash on and off as normal. I have replaced the flasher unit and the bulbs (both front and rear) and cleaned the socket contacts (also both front and rear).
I have not replaced the sockets nor measured the actual voltage level that is coming through the wire to the right-side sockets.

Got it sorted out. Went back to my wiring diagram. Found that the flasher in the fuse box controls the hazard lights only. Digging under the dash I found the second flasher unit and replaced it. Up and running now. I appreciate your time and your site. It's good to see a site that helps DIYers like myself. Thank you.