You might try bobbin washers. They help the bobbin turn smoothly. This is an idea from Leah Day.com. I know I keep saying this but she has the best FMQ ideas I've found. Good idea to let it rest for the night! Keep on trying, the small test pieces are a great idea, also.
When I get frustrated I also like to read the Bitchy Stitcher's blog. She will make you laugh out loud!