300xs starter problem?

[Revolution141]

When I hit the key to start it throws the pinion on the starter out and engages fly wheel ring gear but won't wind over. If I keep hitting the key it eventually fires. Changed starter solenoid, no different. I was thinking brushes but I can't find where you can buy brush kits anywhere for these starters?
Am I on the right track?
I pulled the starter down and cleaned up with no difference. I noticed brushes are all connected to plate via wires and this plate is held to housing with torque head screws. Anyone know where I can buy these brush assemblies?

[Euroski]

What's the voltage at the starter while cranking it? Got to make sure it's getting enough volts first...

[Revolution141]

I'm assuming voltage is fine, although I haven't actually checked. I only say this as when it does finally wind and engine fires it is very strong and quick, as well as the fact that the smartcraft says voltage is fine. Can't check for another week as I'm away from home but will double check when I'm home

[Revolution141]

I did end up checking voltage at starter and was all good.
Back to original question, can I buy brush assembly for these starters?
like everything else on this motor I'm guessing merc expect us to buy whole new starter!