When I made myself a small hand sanding block, I discovered that the paper would load up with dust and become useless within a couple of minutes. I glued a thin sheet of some kind of foam rubber I found onto the bottom, which cushioned the paper just a little. After that it worked fine.

Your story reminded me of this. I can’t remember what prompted me to put the cushioning on, but it worked like a charm.

Losing fingers since 1969