Dropped valve??

Bighead440 said

Nothing appears to have been touching the retainer. Everything looks new and oily, that's it. The valve has a nice short sweep pattern clearly visible on the intake side of center, but not off much from perfect. Just NO LOCKS, they floated away in the oil I guess.

Click to expand...

Strange. I would rotate the engine and watch the rockers through their sweep to eliminate the possibility that the rocker unlocked the retainer "somewhere" in its travel.

I wonder if maybe the valve locks just "failed"? How does the valve look where the locks wrap around it?