I will not accept the perceived incompetence you claim, by your own admission you’ve not been on for a bit because all the things you attended to on previous visits are functioning correctly & have kept you away.
I’m certain you will be familiar with the 1/4” “lucar” connector, ubiquitous to all cars with a Lucas lineage, the 375 is a larger version of the same thing. Standard crimp on 1/4s are usually red for thinner cable & blue for thicker, you may also come across yellow versions which take even dumpier wire which is capably of carrying more current than the connector will adequately take.
Thus the 375s are usually yellow indicating greater capacity, an auto factor will have these & I would recommend the fully insulated verity.
The Method.
Equip yourself with a GOOD pair of crimping pliers, safely lift the rear of the car, scrabble about underneath until you locate the bastard thing, cut the miscreant piece off, strip back a suitable length of insulation & with your good pair of crimping pliers affix the replacement. The rest you know.
Do report back, all too often advise is given based on experience, a report either way reenforces, or demolishes that experience. Most information on here is empirical as no Haynes manual exist for our cars & even though we have an excellent library on the site, a quick question on here, if answered accurately can save hours. M