That made a lot of my early troubleshooting calls with our modems & various home computers in the 80's easy, as our modem used the same Domino Din & users were told, remove & rotate the modem plug 180 degrees, then reinsert if the modem wasn't dialing out.
Super easier still for Beeb owners, they had a choice of which cable end to unplug & rotate.
I wish someone had had the foresight to include this troubleshooting fact in the manual(s) though.
Biting the hand that feeds IT
