oil pressure and adjustable hydraulic valve adjustment

Thanks to all who replied.
I have reset the valves. But I think I found the problem. While adjusting, when I got to the #6 exhaust I found the rocker arm floppy. The adjusting screw was tight,so it wasn't because it worked loose. I adjusted the screw, but it left no threads visible. The other adjusting screws have 3-4 threads showing.

Does this mean what I think it means?

What needs to be done at this point? How can I confirm my suspicion?