To ask in the vintage thread, go here and 'reply'. Someone will help you.
http://www.quiltingboard.com/t-43881-899.htm#2951235
WD40 might help, but be sure to clean it all off when you're done. Don't leave it on the machine. I'd use a pair of big pliers instead of the screwdriver. Your machine may be a candidate for a kerosene bath.