Thank you Bob, Mike & Bruce.
I discovered there are also 2 capacitors tucked under the choke.
I put photos here, hope they can be seen:
https://postimg.cc/gallery/t4rzxeoq/I'm happy not to use an AVR if it works OK without one. They are surprisingly expensive.
As they have no battery to charge, it's a mystery to me what they do.
I found a manual, but it's of the type that has several wiring diagram variations, all confusing.
Good news is that there's an old guy lives nearby who used to rewind all sorts of electric machines, who came over to check it out.
He took some coil resistance readings and says it's good prospect, so I will now make up mounts for it, and organise the belt transmission from my Lister CS1.
Jordan