The tech log entries I have seen refer to 'unknown contaminant on turbine blades' etc etc. After assorted checks, the CRS states 'within limits' or similar.
But this 'unknown contaminant' could be almost anything - pollution, quarrying near the airport to name but two - and could have nothing whatsoever to do with the unpronounceable volcano. I am also told that there is (was) no baseline sample from the volcano, and until that happens the contaminant cannot be linked with the volcano.
In other words, if all engines had been subject to the microscopic internal scrutiny that they are now, 'unknown contaminants' could well have been found before the volcano, and could have been irrelevant.
Aside from the full strength Eric Moody volcano encounter, the major problem is surely going to be erosion and performance degradation - and that won't be apparent until engines are prematurely removed in the next few months. Our Lords and Masters are most likely barking up the wrong tree (imagine my surprise).