Mechanic's Neglignce?

Hi -- I'm looking for a little advice. Got my boat after the yard serviced the lower unit (Volvo) and didn't tighten up the gear oil plug. Soon got a high pitched whine and the engine quit. The yard owned up to not tightening the plug and drained out the lake water. They filled it with gear oil and told me "all set." Well, it still whines pretty loud around 2400 rpm and there's a low rumble at idle speed that wasn't there before. Really sounds like bearings to me. I brought it back again and the shop claims they're not hearing/feeling anything wrong. Any advice on A)what's wrong and B)how to approach the shop? Seems like this is their problem to fix. They're my home marina,too, though, and I don't want to alienate them. Thanks.

Yeah they should tear it down for inspection on their dime. Unless you also had a gimbal go bad at same time yes bearings in drive are screwed... ironically the bearings prefer oil over water as lube .

Bottom line if the situation were reversed like they had installed a new drive you winterized it yourself made the same mistake and brought it back in for gear whine... there’s no way they would honor the warranty on the drive because you ran it without lube... there shouldn’t be an alienation , they messed up no way the drive was not harmed

Thanks. Good analogy about the warranty. I can’t imagine a gimbal went at the same time — when I say the failure happened “soon” I mean ten minutes max. Flushing it made it drivable but I don’t trust it. Plus, it turns out the oil service was done in February so the drive had two solid months to leak before it went in the water.