Not actually today, but replaced the clamp for the negative post of the battery.
About an hour in, I had the recalcitrant and defective old part in my hand, a couple of grazed knuckles, and the realisation that the lovely new part, the cheap as chips part from ebay, would not fit. Turns out that these things are handed and I needed the other handed (mirror image) one.
20 minutes with a hacksaw and file sorted the clamp itself - I cut away the unneeded part that was fouling - and another 10 minutes with a scalpel fixed the plastic trim piece.
Then discovered that the square head of the bolt used for tightening the clamp onto the battery post has pre-rounded corners (why?) Except for one. And that's all I would need to get the necessary reaction to the torque I would apply to the nut to tighten the clamp onto the battery post. So I carefully reassembled it with the one good corner biting, tightened the nut with my dinky little socket that just perfectly fit in the hacksawed gap.
Two hours in and the engine was running and I was resetting the clock.
Happy ending.
All still perfect a couple of days on