Does anyone know what the size is for the Mini-Din Stereo Headphone jack on 757/767/777's in COs fleet? Is it a metric or imperial sized plug?

Reason that I ask is over the last few months I have had numerous problems getting a nice tight fit into the jacks on multiple CO aircraft. At first I thought it was my plug but more recently I have been able to rule that out.

Also I wonder is CO replacing the current headphone jacks as they upgrade the 757s to AVOD, last night flying TATL on a 752 the one inside of my armrest was broken from its mounts and falling around inside the armrest. The seat next to it was better but still loose in its mount. I have also noticed this one more than one TATL flight as a minor problem.