I have recently been in touch with a person that has successfully rewound heater coils for his No.670 Weeden, he has agreed to share his experience:
"I’m happy to share details on how I wired it…
I didn’t know what size, so I bought a nichrome wire assortment on Amazon. I used a caliper to identify the wire that was the closest and that was 26 gauge.
I wore rubber gloves so I wouldn’t get oil from my skin on the wire and used a scratch awl to tightly wrap the wire in boiler length strips (about 4”). I’d pull the scratch awl out and leave about ½’ straight for the return and repeated this 6 times. Once six coils with ½ between each is complete, I assembled back onto the ceramic, re-connected the wires and voila! It’s not perfect, but in all honesty, it’s about just as neat as it the wiring was originally."
Disclaimer:
This is for information only, use at your own risk, the information came from an engineer working in an experimental lab so knows that he is doing.