Centaurus: I think you've put your finger on the core issue.
My experience is that an instrument scan, if not often used, atrophies. It takes a bit of work to get it going again. The time to do that is not "when you need it the most" but before you need it again.
Final report hopefully will have a bit more granularity in the analysis. (I don't yet understand what is going on with the EPR changes, but I have not had a chance to go through it a second time. Sometimes one sees something else after the initial read).