Originally Posted by JoeJr

I wouldn't remove it all the way yet. There's a long spring under it and there should (might) be a washer at the top of that spring, so be careful with the adjuster screw all the way out. Once that screw is out I use a small steel bristle brush over the threads then my thumbnail with a rag over it in the threads at the top, unscrew it with my thumbnail in the threads to clean out debris, then some oil at the bottom of it before I screw it back in. But this is usually one of the last things I'm cleaning when putting a machine back together after servicing. There is a lot to learn, but it gets much easier the more machines you clean (and you will acquire more vintage machines). Search this board, search the internet, and ask questions, people are very willing to help, and I have learned (and still learn) a ton from everyone here.