Hello, Rik - We are sorry to see that the medium bristle brush on your power scrubber isn't suitable for your needs! If you are looking for a tougher option, the A95HRB9 9 in. VORTEX Hard Bristle Brush would be a great upgrade. The hard bristles are ideal for cleaning brick, concrete, rust, masonry, and more. You can find that brush by searching model A95HRB9 on HomeDepot.com or by utilizing the link below. We hope this helps! And feel free to email us anytime at Reviews@RYOBItools.com, if you'd like to continue this conversation.
RYOBI 9 in. VORTEX Hard Bristle Brush A95HRB9: https://www.homedepot.com/p/RYOBI-9-in-VORTEX-Hard-Bristle-Brush-A95HRB9/324055239