I had a 1966 Hercules & the model escapes me. It was a Raleigh Sports clone made in the USA with Raleigh parts. The headset was binding. Bike shop & I dediced to replace the headset -- dumb idea. Actually it was probably that the head tube and/or fork crown needed facing. There was nothing wrong with the balls or races, they were like new (as was the rest of the bike actually). Never got it sorted out, sent it to its next owner with a new headset that was either too loose or binding.

I don't still have it, else I'd offer it to you...

Did you see Sheldon's page? Can use ISO parts on the bottom half ...

Quote: [For headsets as well] as with the bottom brackets, Raleigh differs from B.S.C./ISO in using 26 threads per inch instead of 24. Fortunately, all of the other mounting dimensions are the same between the two systems.

* The adjustable race is octagonal, 1 5/8" (41.4 mm) across the flats.

* The lock nut is also octagonal, 1 1/4" (31.9 mm) across the flats.

The stock Raleigh headsets have proven to be unusually long lived, so it will rarely be necessary to replace one, unless you wish to install a non-Raleigh fork.

You can even mix and match. If your Raleigh headset cups are worn out or rusted on the load-bearing bottom section, you can replace just the bottom with any standard ISO 1" headset parts, and re-use the Raleigh upper assembly.