All's well that ends well.
https://road.cc/content/news/ebay-selle ... fer-280079

EBB.
Does anyone service their EBB? Mine is the split shell with pinch bolts on the bottom so an open slot at the bottom.
The HT2 BB is contained in the sealed(?) EBB shell so protected from crud but every time I see the open slot it just makes me wonder.

Chain.
Is it possible to determine chain wear using vernier callipers or do I need a chain measuring tool?

If you can accurately measure the distance between the centres of the pins, you should be able to calculate chain wear.

If your going to measure a chain with verniers you need to go center of pin to center of pin over 10 pins then divide by 9 , but you’ll need the original chain pitch to see how much is stretched , , maximum wear on lifting chains is 2% but on a bike chain I have no idea , the reason over 10 pins is it’s way more accurate than measuring between just 2 centres , tbh you’d be better just buying a chain gauge as they are more accurate and do all the calculations for you

The guidelines I've seen for chain wear replacement is 0.5% on 12 speed, 0.75% on 9-11 speed, and 1% on the rest.
Topeak do a really small, light chain wear guage but it only has a 0.75% setting.

Impressed with the Electrical company’s response.

I take the bushnell one in the Jones to bits, clean, re-grease and refit once a year or so. I made up a couple of caps to keep the worst of the gunge out but as I'm moving it quite a bit to tension the chain its worth giving it a good clean from time to time.

i dont ever take mine apart but i do make sure it can rotate

Once a year remove ebb assembly,it allows any water out that may be trapped in seat,down and chain stay tubes.
Clean and dry everything,smear of grease on mating surfaces, reassemble,and retension belt /chain.

Using verniers is a faff. (Yes I learnt the hard way too! )
Just buy a park chain wear tool,part no. CC-3. Has 0.75mm and 1.0mm wear measure.
Takes seconds to drop in on several points around the chain to get an average.
Rarely used, I run two belt drive bikes now!