Looks a bit crusty in parts, guessing it's been stored outside for some of its life, and may account for gear change problem.
On my recently acquired Stowaway, there were a couple of issues with the indicator chain. It had been over tightened at some stage, and twisted badly as a consequence. Upon removal to straighten it out, the shaft appeared to be a bit on the longish side. It was indeed too long compared to others of that era in my possession, so a replacement was fitted from my spares department.
So far so good, then onto the elephant in the room, the grip shifter. A more modern one fitted (will do till a trigger shifter comes my way), and all gears change perfectly now.
I believe you're comfortable with dismantling the hub if necessary, and you're welcome to any spare bits I have from a hub of around that date.
I'm glad your grubby hands are getting more grubby now - keep us posted