[Jim A]

My 1960 1500 turn signal switch failed decades ago.
Maybe there was a way to fix the part that turns off the brake light while turning, but I could not figure it out, so I installed separate light fixtures in the back and ran the whole works with a three-way toggle switch.
That part still works just fine, and the indicator light did too for many years.
When it became intermittent, a little wiggle of the bulb fixed it. Until it didn't.
Then I pulled the dash out and found a small break in the printed circuit and managed to bridge it and enjoy several more years of a nice bright indicator and avoid the dreaded flashing away while driving (the noise in the cab is just a bit louder than the flasher).
A recent similar "fix" has proven transitory and resistant to further repair.
Maybe I could install a whole new light somewhere, but I would rather one of you has a magic approach I haven't thought of.

PS: It made three smooth trips with about 2500 lbs of hay each last week. One of them was on a three mile straightaway with the above mentioned flashing and the poor guy behind me wondering when the **** I was going to turn.