Molly, I use these and they seem to help a bit for stitch consistency on machines like yours that don't have any kind of "springy thing" already in the bobbin case. It seems to make some improvement when I'm stitching at high speeds.
And, If you don't have anything inside your bobbin case, of course you don't need to take anything out. I have a few different machines, some I use the Little Gennie washers in, some I don't need to because the do have something already in the bobbin case to tension it and help it feed more consistently.
I won't totally swear by these things, but I do think they help a little.
The picture shows a bobbin case on the left that has an anti-backlash spring built in; on the right, a bobbin case without one that I use the Bobbin Genie in.
Last edited by azwendyg; 01-22-2012 at 05:52 AM.