I stumbled on a solution. After brief tinkering, (a) “test” appeared in the main shell menu, and b) I could run test immediately, just after selecting the archive, just as it has always done before.
The problem - unfortunately - is that I am not 100% sure what I did. I was tinkering with adding and deleting several other items in the shell extensions menus. (I thought tinkering with the menus might yield a result.)
I THINK this is what I did:
Under compression:
1. removed compress to RAR
Under extraction:
1. ended up with “extract archive to” and “extract archive here.” I either had one but not the other; on even took one off and added it back on.
In any event, shazzam: test showed up and worked correctly, both in explorer shell AND in right clicking within the PA window. It did NOT take to me to the PA windows or require me to actually open the archive. Just selecting it was enough.
If you want, I can send you the new registry keys, and you can compare them with the one I sent this morning. Perhaps you can isolate the exact difference.