the car gives a high pitched whine when started each morning, tends to be ok after that. He has already had 2 starters fitted in last 8-10months by another mechanic and he said it was ok after the starter was changed for a few months but is now back again.

I took starter out to inspect ring gear and there are wear signs - teeth look shiny and similar on the bendix but I have seen a lot worse. Gave it a good clean up and refit - couldn't get it to happen. Customer will let me know tomorrow morning.

Any ideas what could be wrong? Any common issues on these?