I would like to thank evan, nikolasco, and logjam for reviving my faith in the open source software community. You can't get a 24-hour turnaround on bug fixes from a commercial software vendor for any kind of money. My problem is now gone!
When I used logjam in command line format to grep my old entries (the only search I can find that works), it segfaulted. Two helpful replies and two gdb backtraces later, they fixed it and gave me the patch.
Ah--cool. I did not realize it could do that. I've always been using the XML export every few months (i.e. when I remember) mostly as a local backup in case something horrible happens, but also useful for running grep against.