27-01-17, 03:38 PM
The curve on the surface isn't a problem it is in fact a good feature as it spreads the current over a greater area stop local overheating.
The brushes should slide smoothly and freely in their holders. New brushes are 10mm long and the manual gives the minimum length as 4mm. The commutator the brushes are pressed on to should be copper looking but doesn't have to be super shiny but shouldn't have any black areas on in (except for the thin black lines between the bits of copper).
Often dismantling and reassembling the starter motor will free the brushes up and the problem can disappear
The brushes should slide smoothly and freely in their holders. New brushes are 10mm long and the manual gives the minimum length as 4mm. The commutator the brushes are pressed on to should be copper looking but doesn't have to be super shiny but shouldn't have any black areas on in (except for the thin black lines between the bits of copper).
Often dismantling and reassembling the starter motor will free the brushes up and the problem can disappear