Does anyone know what the fuel flow was? Although they probably wouldn't have thought to look at the fuel flow, that would have given them a clue. This, of course is hindsight. I assume that is recorded of the flight recorder.
Fuel flow is not one of the primary engine indications (EPR, N1 & EGT are). At that point on the approach, the handling pilot would have had his hand resting on the thrust levers and would have felt the autothrottle moving them to increase power, due to a shortfall in airspeed, which would have also been noticed on the PFD. All normal so far. What was abnormal was the lack of engine response to this movement; not long afterwards this was picked up by the crew and at that point fuel flows became irrelevant.
The differences between the power setting required for the approach and the ones the engines 'hung' at weren't huge. From what I remember it was 1.02 & 1.03EPR with 1.03-1.04EPR/48%N1 needed for F25 and c. 1.06EPR/55%N1 for F30.