incremental backup after restore
It threw a "Warning: One or more backup paths don't exist"* error on what looks to be the first run after the problem. It subsequently has run two more times, each showing "Success", with either 0 files backed up or, oddly, 1.
When I go into Backup Storage, all of the paths exist and files appear to be where they are supposed to be. So, crossing fingers, it appears to me that I can do "Synchronize Repository" and all will be good.
* Might need to convene the High Grammar Court on that error message :-)