I should have tried this ages ago!
I finally gave the steam method of removing a knot a try, and I wish I'd done it sooner. The Rubberset knot practically jumped out of the brush, it was so easy to remove. Not only that, but I was able to save and reuse a knot that I put in one of my first restores, but had set at much too high a loft. The vintage Rooney, however, is proving to be a much tougher customer. I guess that's the difference between a high-end brush and a cheap brush. I'll give it another go later this week and see if a longer boil will shift the Rooney knot.
When we remember we are all mad, the mysteries disappear and life stands explained. - Mark Twain