A year or so ago I removed what was supposed to be a 25mm knot from a Semogue brush to fit it to a handle that had a 24mm knot. I was worried that the knot was going to be slightly too big but it was not, it had 2mm to spare so I don't know what was going on there.
Then, with a similar handle, 24mm knot, I fitted a 24mm badger knot that I bought from Maggard and it was also a very loose fit.
I'm toying with the idea of re-knotting another brush that has a Shavemac's knot that I don't like but I love the handle. I need to find a good badger knot for it that is reasonably priced, not a Maggard knot, it appears that unfortunately Maseto dont do badger knots anymore.... I'll find something
Cool if you soak it in hot water will it soften enough to scrape it out ? Or if you have a dremmel type tool you carefully use that to remove it.