We play with Alfa’s now. Just say no to all of this and go to a proper joint. 

That does seem a touch low. On my DG's at work I usually find fresh filters and oil starts with a differential of around 0.4Bar, and usually I take notice of the differential when it reaches 1.0Bar. 1.5 Bar is when I would replace the filters. For "clarification", when running my DG's usually have a LO pressure  of approx 5 Bar. Phil

Turns out the Mann equivalent to the Wix WL7138 is Mann 714/2 💡

I know. Poor thing.  I think a lot of work has gone into making sure it cools.    not sure that will be an issue here !  

The reviews I read about complain that the jack is still on wheels, no matter what it can't solve that. But it does provide an extra bot of security, just not probably £100s worth was my conclusion. If it were £30 no brainer. Anyone looked at quick lifts? I'm intrigued how they hit the jacking points correctly. See lots of mobile mechanics using them.

Current favourite with me is the Mann 714/2. 79mm long. Internal relief valve 1.5 Bar. Twin anti-drain flaps.  https://www.mann-filter.com/au-en/catalog/search-results/product.html/w714/2_mann-filter.html   Slightly random…. but perhaps relevant, I’ve just looked up what Mann consider to be the filter for the Triumph small 4 and it’s the 713/14. Bypass on that is rated at 1 Bar. Relatively few choices for that application thanks to the unhelpful 5/8” thread.

Following on from Nick's comments. If there has been a previous failure of the countershaft/needle rollers with the bushes that are in the laygear cluster then it is quite possible that this caused brinelling on the bush which would leave microscopic ridges on the running surface and therefore accelerate wear. For my tuppence worth though the location of the failure on the shaft suggests that the bush in the laygear is not exactly parallel to the axis of rotation.

Was thinking the same thing…..

Sunburned feet…. And suddenly all your shoes have teeth….

This ^^^^ Based on my admittedly limited knowledge of fluid dynamics from university 40+ years ago (and before CFD came along) I am unconvinced of the merits of a taper design from what I have seen, particularly on normally aspirated engines. And whatever benefits there might be, it seems to be far easier to get it wrong and have something that reduces performance. Whilst also being harder to make that a simple design.