Thomas,
Unlikely that you'll find an actual replacement source for these, however you might try soaking the brass in ammonia for about 30 min and it may make cleanup of the existing parts much easier. Not a guarantee but that's what I would try first. If successful not too difficult to adapt supply house felts to that, or make your own. Not rocket science.
Peter Grey Piano Doctor
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Peter Grey
Stratham NH
(603) 686-2395
pianodoctor57@gmail.com------------------------------