I had the gears go bad in my lower unit on my 130 last month.The dealer said he shimmed the new ones. Last week after running it for two hours I checked The magnet screw and found some shavings. No metal chunks like before itwas bad. I took the boat out today and ran for three hours. I checked the magnet screw again and still found some shavings. Is this normal after new gears are installed.