I only needed to replace the broken brush, but I bought a new set of brush, wheels, and filter that is cheaper than the brush alone. So, I replaced them all, NEW brush, wheels, and filter. Then, I kept getting Error 2 after every 30 seconds. It was so annoying. I noticed the Roomba ran slightly higher than before. It was about 1/4 higher than the carpet, now it is about 3/8 higher. I installed the old wheels back and SOLVED the problem. It is working on sensing the height. The new wheels pushes the Roomba up and it thought there were debris there. No more Error 2!!!