Take off horn button and horn parts and observe operation of the lever to determine right turn lever issue. Sometimes a mechanical issue can be fixed. But the plastic/nylon parts involved are hard to restore when cracked/broken.
You are troubleshooting brake issue. FYI or reminder: Brake switch sends signal to T/S unit. Flasher sends flash to T/S unit. T/S unit is a router. It shuts off brake light signal to allow flash for whatever turn is signaled. So test brake lights, with no turn indicated, to see if they both come on. If they do, test probe the applicable wires/terminals to see if voltage is present, using explanation of operation as a guide.
Notes:
1. This lever problem is right side, same as brake issue side. Clue??? Don't know.
2. Shine up the brass male and female contacts of that firewall connector mating pair.
3.
On sale. Quick fix if it's the actual electrical switch part of the assembly.