The mica undercutting is good as long as it isn’t too deep. If the brushes are too soft the undercut will fill and cause arcing over on the com. Make sure the brushes are profiled correctly to the com.
Mr.Rooks;Thought I had subscribed to all posts but no alerts to your reply were in my email.I have about 30 starts on my regrooved/undercut starter.And I did not take extra care with the original brushes on commutator profile matching. So far,so good.Don L.
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