Rusty (as the other guys have started calling you
),
What you describe in your first post does not sound like a bad segment/open connection at the commutator. This would give you an intermittent operation if the brushes stop on a dead segment/bar of the commutator. Once the armature starts to turn it would build enough momentum to keep turning but you would get arcing as the commutator segments or bars pass under the brushes. Once the armature stops with a brush on that bad segment, the starter would not turn on the next attempt to start the car. What it sounds like to me is your brushes are worn down to the point that they are loosing contact with the commutator bars, or as someone else mentioned the solenoid is going bad or another possibility that I just thought about... could the battery terminal connections at the posts be making poor contact, I.e. corrosion build up that just needs cleaning.