Ruh roh Raggy! I hear you knocking…

[idahovette]

Is it a metal or plastic cover? Oh sh!t never mind it's a manual!! duh oh...read and comprehend, right??!!!

 

[JBswth]

@JBswth, it was the inspection cover, apparently. They pulled the cover to check inside the bell housing area, found nothing of concern, put the cover back, started the engine to use a stethoscope to track the sound, and the sound was gone.
The only thing we can think is the cover was put on in just the wrong way that something inside the bell housing, something spinning at crank speed, was tapping it. I have had the engine running several times now, and the noise has not returned.

That's good, maybe something was in there and fell out unnoticed.