I have just caught this virus, which I would call, for want of a better name, "Old Sewing Machine bug."
I have a 401 that I bought for 30, and I just snapped the cover plate spring. I also just inherited a 501 with a busted spring. So, I can see that black screw, which clearly is all I need to get at to change the spring, and I have another spring from a totally busted 503 that somebody also gave me. (Yes, sewing machine velcro might be another term for it) but how do I get at the screw to remove the busted one and install the new and/or used one in its place?