Disconnect machine from mains.
Unclip black fan cover clips (protect eyes from brittle one which pings off)
Remove the metal spring clips
Undo 2 screws holding brush clamp
Ease brush out (remember orientation of brush or take a digital picture)
Carefully insert small flat bladed screwdriver where the spade connector is and ease it out
Put spade connector fully into new brush. Be careful with these these the wire breaks easily
Fit new brush making sure the bump on the brush fits in the slot
Refit clamp
Refit spring clip
Repeat for other brush
While the brushes are out I always clean the armature with very fine emery and then with a pin remove the carbon from the slots and wipe clean
Put the fan cover back on and test
Swear because itś unplugged, plug in and test.