Hotpoint aquarius WMF720 flashing H20 and F02?

My Hotpoint aquarius WMF720 flashing H20 and F02. It doesn't spin and sometimes doesn't drain, but it can drain as if turned on and off it drains it self. Does this sound like the carbon brushes. The belt is ok and I have checked that all the filters are clean. Is it easy to change the carbon brushes in the machine.