Isnt there also a problem with backup batteries.
The batteries fitted on the 40 are very small and I gather have been found in a state of very low charge. Their life would also seem to be poor. I guess there is a positive check however in that I think the red button on the ECU panel on the 40 switches the ECUs to run on the backup battery and so presumably proves it is functional. However I am not certain this exists on all versions of the 40 ? In any event if a backup battery was the solution presumably some form of proving the backup would be required on the 42 ?