The pictures posted back a few years ago by Wim Blees shows something more like powdered soap , type in UST-K8C in the Search box and on the 3rd page you will see his pictures. Your pictures almost look like hammer felt - maybe there are rodents at work. I had to replace all the hammers in a Petrof Studio they all had been shredded by mice
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James Kelly
Owner- Fur Elise Piano Service
Pawleys Island SC
843-325-4357
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