a lifted commutator segment will give a clicking sound and also will cause arcing when the brush gets lifted off of the armature.

i have had success in the past using a very corase comm stone on the armature, they can cut alot of material off the armature so be careful finish with a fine seating stone and replace the brushes with dealer supplied ones (aftermarkets are no good i have tried them all) watch out for the drive motor fan when the motor is running!

a motor replacement/rebuild is always an option as well.