Bad Parts again?
The refurbishing of the grarbox, and probably the epicyclic gears too, makes me think of old stories about bad spare parts being resold as new. The husband of by secretiry died as pilot in an accident over the North Sea when a bolt broke making the plane lose its vertical stabilser.
Is there a system with numbering of each part in a gearbox which would certify that old parts are not saved and reused several times instead of new parts.