Leaking oil pump, new oil pump, now loud knocking coming from powerhead

2015 250 pro XS purchased new in June of 2016. Serial #2B113975. Model #1251P73BD. Ranger 520
2 months ago noticed oil on steering, after inspection realized it was coming from pan/cowling. Removed cowling and traced oil back to what I learned to be the oil pump. Took to local dealer and diagnosed bad oil pump. 7 months out of warranty (3 years). Googled merc oil pump problems and got many hits so asked Mercury to help me out. After several phone calls merc agreed to replace at their expense. Dealer replaced oil pump and did another $400 worth of regular maintenance. Engine ran as new for 6-7 hours, then Sunday when almost back to launch I thought I heard something different while running about 30 mph, sounded like a slight knocking sound. Came off plane to idle and engine sounded terrible with loud knocking which I believe was coming from under cowling Took back to dealer but they haven’t gotten to it yet.
Would the leaking original pump caused this? Would it have lasted 6-7 hours? I sure hope I’m not looking at powerhead replacement due to oil pump issues. Dealer has always treated me and others fairly with good reputation.
Any advice if diagnosis is blown powerhead?
Thanks in advance for replies.

Let's wait for the diagnosis from the Dealer, that is laying hands and eyes on the motor, BEFORE the speculation starts.

+1... Need to give the dealer a chance to diagnose the actual failure (as well as perform a "cause of failure" analysis).

Dealer called, said air compressor was bad. Said it was getting oil.

That's a heck of a lot better than a powerhead.