As suggested above, the trouble might be right in the TS column switch.
Make a truth table/ chart of the colors going in/ out of the switch and what they do. On something that late, the hazard switch is built into the TS switch, and it too can be a problem. Wiggle the heck out of it and try again
What goes into the column TS switch
Switched power from the brake light switch, which is powered at all times
Full time power from the hazard flasher
Key switched power from the turn signal flasher.
There are no ground / grounding circuits in the TS switch
Outputs:
Left rear turn/ stop
Right rear turn/ stop
Left front turn, which branches to feed the indicator lamps
Right front turn, which branches to feed the indicator lamps
With the TS switch centered, the turn flasher feeds nothing. The brake switch feeds both rear lamps, tied together
With the TS switch to left, brake lamp power is routed only to the right, and turn flasher power feeds both left front and left rear.
Opposite of course, with right turn
With the hazard switch engaged, it ties ALL output lines together, the outgoing rear brake line and the two fronts, all tied to the power from the hazard flasher