SD60 new boat issues

[Tracyandkimo]

Hey,
Went to take delivery of my new L46. Literally getting ready to throw the dock lines off when I noticed faint prop wash coming from the strb side. Made sure control was in Neutral. Shifting into forward - no problem. Shifting into Reverse - grinding sound. Still no neutral. Broker reports that this saildrive was replaced due to unstated issues shortly after they took delivery. Awaiting response from the Yanmar tech in Annapolis, Yanmar and the broker.
In retrospect, the issue was likely there at the shakedown cruise but went unnoticed due lack of being able to see the transom from the flybridge or hear the faint grinding sound when shifting into R with the engine hatch closed.
Any ideas. I wanted some knowledge so I can discern what I might be told.
Thanks,
Tracy