Never thought of the packing peanut, Nancy, but will definitely keep it in mind if I run into trouble.
I was having problems with monofilament tension until someone mentioned to me that they changed their upper thread tension to 1.5, a lot lower than I would have ever thought of changing it to (I went as far as 2.0 on my Bernina 830). But, at 1.5, my tension problems went away and I had great stitch quality. It may not work for you, but it certainly is worth a try!