Checked all of the above, and finally purchased and installed new brushes ----- and still got the error #2. The engineer in me finally kicked in and I took out the new brushes and looked closely at how they should operate. As noted there are two different ends to the brushes -- the drive ends which are the ends (with the square and hex shaft ends} that must insert into their respective shape. and the opposite end which should be free turning. So when you grab the square or hex end and twist it with your fingers on the opposite ends you should be able to rotate it easily while holding one end stationary. One of my new rollers was almost frozen stuck an the other required a high level of torque to rotate it. When you pull off the plastic end cap of the roller on the non drive end there is actually a brass bearing on the small steel shaft that can be exposed when you take that plastic end cap off. I took a bit of emery cloth and sanded down the shaft, added a touch of WD40, slid the brass bearing back on the shaft and reassembled plastic end cap on the brush. Bingo!! the shaft now turned freely when holding one end. Did the same process for the other roller and an put both back into robot as per the standard replacement process. The robot has been running great with no more code 2 errors. Hope this helps