Updating. Yippee! I think I fixed my stitching problems. The mechanic said to check the bobbin case, as sometimes when they are dropped they fall on the top section and bend in - no longer a circle to take the bobbin. All I had to do was pry open the casing in that spot so the bobbin didn't catch when the thread was pulled. And to think I nearly threw away a couple of bobbins because I thought they were warped.
Just letting you all know in case you have the same issue.