Who likes nylon brushes? This scratches my face and lathers poorly and if it wasn’t for the sentimental meaning and the beautiful handle I wouldn’t have it. What say you?
I'd say get a new Cashmere knot in the appropriate size. Looks just like original but far more pleasant to use.
Assuming the brush uses a 20mm knot. I bought it as the synthetic cream white at Shave Forge because I couldn't find it elsewhere in that size, but I'm sure with some hunting it could be. The knot feels a little small at 20mm but it works. Better than the fishing line the brush comes with.
I once bought a late 1960s or early 70s NOS nylon brush for the sake of the two-tone handle and thought I'd try it before attempting to put in a new knot. It was like scrubbing my face with a yard brush, and produced lather with the greatest reluctance. Unfortunately, the handle fell apart when I removed the original knot, so it was a lose-lose situation.
Mine face lathers well and isn't scratchy. If you look closely it even has split ends. It is super floppy with no backbone so I don't enjoy it. I do occasionally use it for Noxzema.
I had a couple nylon brushes in the 70s-80s. The best of them weren't all that different from today's Omega S-brush series. For years my goal was to get the soap off the puck and onto my face. I never gave it much more thought than that. If a brush didn't cause pain it was just fine. In the past 12 years, however, I've invested more time and psychic energy in finding the perfect shaving brush than I did in selecting a wife. It's really insane when I stop and think about it.