MamaKitty,
i have several 301's (don't ask how many or you will KNOW I am eccentric) and I love these machines! I would be willing to send you one of my verified working bobbin cases (they are all originals) on loan so you can rule that aspect out if that would help? I believe anyone who would quote Leonard Cohan AND have kitty in her name is completely trustworthy. Lol! I know you will return it when you have figured out whether that was the issue.
I love this quilting board! Give a holler either here on this topic or you can just pm me your address if you want to try it? And yes, don't give up! These are bar none fabulous machines! I would trade any of my featherweights for them, lol!