this past weekend i took some of the dense, springy foam that they use to support computer cases, battery backups, etc. with and put some in the jack point covers. i just cut a narrow strip if it wide enough to put pressure on both sides of the cover and stuffed it in. this particular foam is good as it wont absorb water or deteriorate, it also soft and spongy enough that you can squeeze it to get the covers in place but will always try to return to its original shape, pushing the sides apart. ill try to remember to get a picture of one of the covers with the foam in it.