I used the PST crop tool and tried to use scanPST - to no avail. The crop tool worked, but scanPST would fail and say it didn't make any changes to my cropped PST file. I tried cropping various amounts and running scanpst. I used a hex editor and altered some parts of the PST as I read other places. No success.
Reading through someone else's thoughts, I was able to use exmerge to import the PST back to an Exchange mailbox. I was able to do this *without* cropping the 2 GB PST.
This was very annoying, but eventually worked using exmerge. If that failed, I would have had to use one of the many paid PST recovery options. The fact that Exchange will export a corrupt PST is absurd. Why would there not be an error if it couldn't complete the export?