You can replace the brushes in the unit, but they run about $25 a piece to do it. That makes a full set about $100. On the flip side, if you would like us to do them, you can fire the box back to us and we can replace the entire innards for $150. That includes all the bearings, shafts and brushes.
We do have a few stiffer bristle options available, but what we found is that they can actually damage the softer squeegees if the bristles get too aggressive. These would have to be done on an customized basis and would be a bit more cash to switch out to.