First check your bobbin area for any lint. Especially the bobbin holder itself sometimes a tiny piece of lint gets in there and messes everything up. Then check the tension both top and bottom. Monofliment is kinda stretchy, it has some give to it like fishing line. Make sure the needle is sharp.
I just seen your post count.....666..........lol..........keep your cooties on your side of the sewing room...LOL