I am working on a 9W Singer machine that was my Grandmothers and cleaning it up and refinishing it because of rust. I have been unable to get the handwheel off and would like to to be able to clean and refinish it and the surfaces behind it. What is the secret to removing it? I have taken what I thought was the retaining screw off and pounded on the wheel a bit but afraid to get too aggressive. Anyone tackled this before?