I am happy that you were able to get it out. I think the two most valuable pieces of advise were:
1) put a sheet in the middle of the bed, while carefully turning it upside down so the screw doesn't go farther into the machine. As mentioned the sheet will show the tiny screw.
2) DO NOT USE A MAGNET. Anything that you even think could be computerized could be messed up with a magnet.