All will be revealed! Decided to have a go at opening it up and lo and behold I found the pawls. I think the photos are self explanatory, with the pawls set into the hub of the wheel, and the tab in the early photo being part of the inner casing around the hub. It looks like there was a pull out knob and bolt that went through the slot and was attached to the tab. When this tab was slid to the left, the inner case moved around so the pawls opened out, but I'm assuming now that the springs are missing from the pawls. so that will be fun to try and work out replacements! I've arrowed the holes where I assume there would have been springs to throw the pawls out to engage on the lugs of the inner drive.

Does this sound about right to you grumpy?
[Linked Image]
[Linked Image]
[Linked Image]