The part of the connector that fails is the solder joints on the display board's connectors get cracked. Very less likely female crimp or the finish on the header post flakes off and causes a problem.

The weight of the wiring harness, the door opening flexing on the wiring harness, single sided PCBs without plated holes all contribute to the solder joints cracking on the male header pins.

Give them a good look.

With a logic probe you can figure out if the 4543 is attempting to do work. Make sure the latch strobe and display blanking reach the chip and act like working displays. Then see if anything is coming out the outputs again comparing to working one. I hate probing around High Voltage tho and if it was me I'd probably just do the chip replacement at this point. If you are handy with desoldering sounds like you have done enough checking to replace the chip. the 4543 do go bad on them from time to time.