Pindi
Although the switch was considered as the solution, as I understand it there was a series of wiring changes as well as revised actuator stops. I would think that EE (and MoD, et al) were satisfied that the problem had been solved.
As for Mod 2107, don't have any background on this so won't speculate, sorry. I understand there were many mods in the early days in the RAF that involved the flying controls and tailplane.