I appreciate all of these answers. Never heard of a mushroom brush (?). My new Fiskar was skipping 3-4 times each pass through the fabric the very first time I used it. I am not slanting the blade. I have tried new blades and am careful to put everything back together properly. It a darn mystery. I looked at the June Tailor mat closely and there are cut marks in the pad. I have hardly used it. JT mats are plastic and not self healing. It is the blue one. Maybe I just need to invest in a new bigger self healing Olfa mat and ditch the JT one. I have decided that it must be the JT mat that is dulling my blades with those scratches in the hard plastic. I think they affect the blade the same as if I had tried to cut over a pin (which I have never done.)