Well, BOAC, I'm not sure how much is or will be revealed about this all, but: as someone has explained, there's two independent readout systems, using different physical prinicples, for each thrust lever. The readings from those systems, which are themselves redundant, is fed into two different board systems (FADEC and FMS iirc?) so there's two data paths that technically will only have one linking point: the lever's bearing point on the frame. If data ca be obtained from both sources, I think we can be rather sure of the actual lever position, despite the fact that we might not have direct indication.
pj
as an aside:
this thread in itself is an interesting animal. It swings from being unbelievably frustrating for people read AB or B and go on a crusade against B or AB back to being very constructive and well educated. It's also probably one of the longest running threads I've ever been involved in...
An amazing amount of information has been amassed here, but also, I think there's an amazing amount of discrepancy in what should have been identical information.