Variations on Fin Nors

[UKChris1]

I'm currently trying to return an abused 6/0 single-speed to a functional condition for a friend (think:  bearings seized so badly that all shafts turn inside the inner race without the bearing itself turning! think: inside all coated in varnish - oops, dried grease and with lumps of coffee grinds that are dried bits of grease; oh, and lots of dried salt too).

In studying the various schematics and photos, I've noticed a lot of small variations between different examples of the same model reel as well as my challenge reel not being quite the same as any of the 6/0 schematics I've yet found.

Challenging...

[UKChris1]

All back together and working as it should. Nice bit of kit and has decades of life in it. I've enjoyed working on this, my first Fin-Nor. Thankfully, the bearings weren't pitted and now run freely.

I wonder when it was made? Can anyone help? The serial number is 688 and is a size 6 (6/0).