Good armature maybe needs new brushes

Question

I have a G4 kirby. Can you replace the brushes? If so where can I buy them? My armature looks good but I think my brushes are bad. I cleaned the armature with a pencil erasure and it worked for a little while then I noticed alot of blue sparking on the armature.I could not get it to come on again. I think this is due to carbon build up. Can I clean the brushes out and be fine or do they need to come out and replaced. My vacum is 11 years old? What do you suggest