Something is impeding the drive train. Usually, it is the brush loaded with stuff it picked up. If the brush is clean, it obviously is not a clogged brush. The next step requires you to disassemble Roomba. Take brush, roller, and brush keeper. Easy part. Remove the bottom plate. It is held on with screws. Don’t lose them. You also mustunscrew and remove the circular sweeper thing. The bottom should come off. Now you must remove the entire piece that holds the brushes. Careful because the motor wires are attached. There is enough slack that you need not - and should not- unwire the motor. The piece that holds the brushes comes out. But not easily. There is a spring plastic catch right and left. You must depress both simultaneously (takes two hands), grip the brush holder piece (third hand) and hold the body of roomba attune rear (fourth hand), and pull the assembly out (fifth hand). People with five hands find this easy. It is almost impossible with only two hands. The entire green thing comes out. Including the gear box on one side. Carefully disassemble the gear box. Five or six tiny screws to keep track of. Lift off the cover from the gear box. There are several Teflon gears. They just slide off. Remember which one came from where. Likely, each gear will have accumulated sludge, and the axles will have strangled themselves I loose threads. Clear everything.. put the gears black in. DO NOT CLOSE UP YET! Spray everything in the gear box with WD40! Very important Now close the gear box and reassemble everything. The two front spring clips on the front of the brush housing will fight you. There should no longer be error 2. The brushes weren’t clogged. The gears were gummed up. Stuff migrates into the gear box over time. You have to execute this goat rope every year or two. There is not much to the Roomb@. All that’s left is the battery, which is easy to replace, and the motor, which is easier to deal with than the gear box was. Most of the functionality is in the electronics.
Almost none of these instructions come with Roomba or are in the manufacturer’s website. Phone help is clueless. You do not need to trash the Roomba or pay for repairs. Good luck. Remember that persistent Error two does not mean that the brushes need attention. It means that the drive train is clogged!