Well... I think the SSD is dead. I'm on my laptop right now. The system did a slow crash again, icons disappearing, garbled text, etc. And on restart, the drive isn't even detected. I went into the system setup, and it doesn't even show the SSD anymore, but all other drives are present.   I thought an SSD would live longer. Only 7.5 years since I installed it. I have HDDs twice that age still running (like this laptop.)

I'll run the smart utility this week and post results. If it is a bad drive, I'll go with the replacement SSDs suggested earlier. (As of this post, it's my day off and I've done nothing relaxing since I started this topic, so I'll deal with it later as long as it runs the rest of today.)   Edit: I do have a question about running that utility. The drive my system is installed on is sda2. When I run the utility, do I type sda2 or just sda? If I've got this right, sda is the whole drive, but sda2 would be the partition, yes? When I run fsck, I run it on sda2.

Looks ok to me. Follow the instructions in the guide I gave to be sure though.     

You could get a four port one,   https://www.ebay.co.uk/itm/116614824260   with four 512 GB nvmes you would have 2 TB of storage.  🤣

SMART data from the Disks utility, if this helps anything.