The important thing is to get wire with the same ohms/metre resistance. I bought a 500m reel for about a fiver. I just haven't got round to using it yet. I've got a few knackered ones to rewind. Some of the Beetle/buggy ones are on parallel cards that the wire is wound on but they all have the bunched up winding at each end. I didnt notice any notches on them though; that would make it a lot easier. I've got one of those magnifying lamps which will help.
I just checked. My old sender is original, dated 1978. The wire is 0.06 mm diameter and there really are fine notches on it, but it needs a magnifying glass to see them. I think it requires some sort of spindle attaching so it can be slowly rotated. I know I couldn't wind it by hand. The picture above on my computer is 4x life size.
I think I've got one like yours somewhere. I'll have a go by hand if there are notches and report back.
I remember my old prototype bay changed it still getting over it! Late Bays are a lot easier good luck.
I had fuel gauge problems, also, my no. Plate light never worked…ever! Then I changed the ignition switch for a new one. Everything works like it should…
The gauge I replaced that wore out had a varying pitch to the resistance wire winding like the picture, but without the waisted bobbin shape for the former, just a flat rectangular plate - probably why it was no good either (that was back in 2010)