Reporting back. The freezer trick didn't do a thing. Testdisk gave me some info, but I had trouble understanding what was what. ddrescue-gui did the job. Copied it all, bit by bit, onto my hard drive, then spent four days (yes, four days!) scraping the last wee bit from damaged blocks. I ended up with an img file, so mounted that and copied the stuff I needed. A handful of photos couldn't be saved, although it did offer the option of trying again, with different settings.
