Stitchnripper

This is my new to me hand crank. It seems to work fine. Got the bobbin cover from sew classic.

I have tried brasso, wadding polish, Maas polish. It doesn't seem to budge whatever is on there. And, lo and behold we have a dremel.

Thing is, I have no idea how to proceed. What attachment? There is a tiny bit of rubbing compound in the box. Use that? Something else?

Also, any ideas on where to get the wood cover that is missing from under the hand wheel?

Thanks in advance!!!