disconnect machine from supply,take off back panel,take off belt and remove both bolts from motor,13mm spanner or socket,the brushes can be replaced if its fitted with a cap end ,i cant tell due to insufficient inf on the model no supplied,the carbons are much cheaper to buy than the full brushes,if the brushes are inside the motor then you will have to split the armature from the field winding,be careful when reassemling ,as the pins will have to line up,it all sounds a bit daunting so if you not sure,call an engineer out because if you burst the motor then it can be an expensive item.
graham
July 2008