The stop is mechanical and it moves freely and returns all the way, but it could in theory still be stuck inside the injection pump I guess, depending on the internal design which is unknown to me.
The filter screen on the fuel inlet however was unknown to me, but when I think about it the connection is "unnecessary" big so it makes sense that there's something there. Definitly worth a check.
Turning the engine 180 degrees and rebleeding was also new to me, it doesn't say in the bleed procedure from Bedford, but I guess it could still be worth a try to hopefully release some potentially trapped air inside the injection pump.
Keeping my fingers crossed that the filter screen is blocked...
PS! Regarding starting spray I've already tried that, and I know how to apply it and that's it really not healty for diesels, and that one must under no circumstances glow when using it. However, since the engine is worn/has a reduced compression the risk is less. The problem is, that the engine starts on the starting spray, but stops as soon as we stop supplying. Strong evidence for the lack of injected fuel.