If this is of any use, my turn indicator was not working altogether with the front screen heater and the hazard lights when putting the heater cable on. Mechanical Heater cable off and all worked fine.
Without further investigation I relaxed the cables behind the dash and the heater cable in an way that it does not touch the wiring any longer when switching on (which means to short its length).
Parts of the wiring harness seemed to be under some tension before.
I managed to do this without dismounting anything, just by using my hands behind the dash where the cables are, reaching from the steering column underneath on a LHD. All is good and reliable now again since half a year.
This is not a failure exploration by cause but sometimes it can be worth just to loosen things a bit. Just an idea because you describe potholes as a cause of mechanical hits.
