Well, for my first step, I plugged in a Zooz Stick that I happen to have lying around, and started to use the infamous PC Controller program.
The goal: eliminate any dead nodes from my Hubitat mesh.
Approach: from the Hubitat settings, get a list of all nodes, by node id. Get the same list from PC Controller. Eliminate (as failed), any node that shows up in the list in PC Controller, that is not in Hubitat.
Results: 6 Nodes in PC Controller that are not in Hubitat.
The standard approach is to mark such a node "as failed", and click on the "remove failed" in PC Controller.
However, such an approach only worked for 2 (out of 6) nodes.
Why wouldn't it work for the other 4 nodes?
I'm not 100% sure, but my following actions point to an issue with the Hubitat Zwave Mesh.
I had a feeling that one of those nodes that couldn't be removed via PC Controller was a GE Zwave (not plus) wall switch that I did a force remove on. (I did a force remove because the switch was probably blocked, and couldn't reach the Hub.) After moving the Hubitat to within a few feet of the wall switch, I was able to do a zwave exclude on that wall switch.
In other words, even though I did a force remove on a zwave wall switch, Hubitat didn't really exclude it from it's mesh. The Force remove was done over a month ago, and it still hadn't been really removed from the Hubitat mesh.
Where is the daily zwave cleanup routine? Doesn't it work?
P.S. I think that the other nodes that couldn't be removed via PC Controller are also old zwave wall switches that I had difficulty removing from Hubitat.