Thanks Max. I took it apart again today to see what's what.

Those compensators keep the emulsion tube aligned. It looks like if you turn the bottom nut up too tight you can start to bend the soft metal. No obvious defects or re-assembly mistakes. Needle and lever moved freely, float seems to float. Tickler works.

Fuel then absolutely poured out in a steady trickle after I primed it. Took it apart again and saw that there was some "black" above where the needle would seat, fuel entry side, i.e. upstream. Gave it another blast with carby cleaner and it looked better. Did not reassemble to test as I figured I might try to save the brass tubes from undue stress. Going to hunt for some new gaskets tomorrow while it is all apart.

Throttle slide seems to want to stick a bit and not close. Will look at that after I've solved the leaking issue.

Some pictures attached for record if nothing else.

Attachments
DSC_0075-01a.jpg (168.38 KB, 20 downloads)
Carby workings.
DSC_0076-01a.jpg (178.06 KB, 20 downloads)
No blockages here.
DSC_0078-01a.jpg (160.83 KB, 20 downloads)
Needle in good shape.
DSC_0079-01a.jpg (179.72 KB, 21 downloads)
Jets.
DSC_0082-01a.jpg (130.08 KB, 20 downloads)
Jet.

I don't collect mowers. I just require Multiple Mowing Solutions™.