I hope I don't give you diagnosticians too much information, but I'm too ignorant to know which part of the story is important and which isn't. I am going to guess that you would rather have as much data as possible, so I appreciate everyone putting up with this.
I used Odin to flash the latest CWM recovery file I could find (0302_charge_recovery.tar.md5) to my ancient Droid Charge, wanting also to flash Superuser-3.2-RC3-arm-signed.zip: after installing CWM I booted to its interface and checked mounts. I mounted system, but each attempt to mount sdcard failed. I tried factory reset, with wiping of the cache and the Dalvik cache, then tried Odin again to reinstall the CWM: failure, failure, then suddenly success! But still unable to mount, or write to, or complete any activity involving the card.
After much long reading and fooling around, eventually tried to use adb-shell to try to reformat the card (with my crappy, rusty old *nix "skills" from back in the 1980s), but got a permissions error which I guess could also mean I had the wrong path, but anyway I am now stuck with these symptoms: I can get into download mode for Odin, but can't boot the OS - it hangs at the Samsung Logo EXCEPT that I can boot into CWM, but any activity involving the card fails.
Also, getting desperate, I tried CI510_VZW_ED1_ALL_ONE-LTE-CP_REV03_user_CL986330.tar (ED1 through ED4) but Odin reports failure at line 1876, or hangs after "establishing connection". Maybe it will work the 61st or 62nd time, but I am beginning to doubt it, so I herewith beg for help. This all seems quite strange to me, but maybe it is routine for some of you guys. I sure hope so. I am way out of warranty. Thanks so much.