Thanks for the quick response. I checked it after one cleaning with LOOT, and it was still flagged as "dirty", with, IMS, 6 ITMs and 1 UDR. I cleaned it a second time, as before, and it was no longer flagged as needing cleaning. I don't know how signigicant those errors really are in practical terms, but better safe than sorry. I've got backups in case I need to revert.