Many thanks to all of you who have replied to my questions. It seems that I've been creating trouble for myself by trying to kludge something together from the old installation. The only reason I tried this was the age-old problem I have whenever I start from a fresh install: I lose all my customizations and added packages that went into /usr, /var, /etc, etc. :-) It takes a while to put all this stuff back; for a month or so after a fresh install I'm discovering (and re-installing) missing things. I was hoping I could avoid this, but it seems that the time I'm spending on my jury-rigged "solution" more than offsets any savings I might realize.
I bit the bullet and downloaded the Debian 12.8 installer to a thumb drive. To be safe, I unplugged the original hard drive to keep it out of harm's way (and to avoid any possible confusion for the installer). Then I deleted all the partitions I was experimenting with on the SSD, and did a fresh install. WOW! Was that ever fast! A complete install in 5 minutes or less! And booting is also lightning-fast. But, as I expected, all my stuff is gone. Well, sort of. I plugged the hard drive back in, and all my files are there. But there are no icons left on the desktop - no more Portal, and none of the utilities I downloaded were on my $PATH. How do the rest of you deal with all the user-added stuff that vanishes when you do a fresh install? Are there some tricks I can use, rather than painstakingly re-installing all my utilities one by one? I assume you can just copy the old /home over to the new drive (although in my case I'll be leaving the big music and video directories on the spinning rust, to be accessed at a new mount point that I'll add to /etc/fstab). But that does nothing about all the nifty utilities that were in (e.g.) /usr/bin (even though the configuration files are probably in /home). For now, though, the box is sort of running. And man, is it a speed demon. Once again, thanks for the assistance. -- /~\ Charlie Gibbs | Life is perverse. \ / <cgibbs@kltpzyxm.invalid> | It can be beautiful - X I'm really at ac.dekanfrus | but it won't. / \ if you read it the right way. | -- Lily Tomlin