[John Milner]

I am rebuilding the original starter to my 71 gto project and have a question on the armature. The armature on the right in the first picture (1970548 GM part number) came out of my 71 gto starter and the one on the left came out of a parts Pontiac starter that appears to have been through a mass rebuilder at one time.

Should the armature commutator have grooves cut in it? The one to my gto feels fairly smooth and doesn't have very deep grooves. My first thought was that it was just wore out and needed grooves re-cut but it looks smooth even where the brushes were not riding. The brushes appeared to be the original Delco brushes and were wore completely out in this starter. The armature from the other starter has grooves cut in the commutator deep enough to catch a finger nail on.

Thanks