FYI...
Inside the rotating black plastic switch on the back of the D2 TD5 key barrell is two rotating copper plates that align with contacts at various point of rotation (you need to drill out two rivets that hold the switch together - not the whole rivet just its head - the assembly screws and it's clips will suffice to hold it together on re-assembly). The outer ring has 3 locting pins that connect it to the plastic part of the switch, to "drive" it when turned. These break off and fall into the switch, allowing "crazy" things to happen, such as unexplained running on.
Of course the whole key barrell etc comes as one piece I was told... With a new key etc or I guess a lock made up to match your own... $$$
I bent some L shaped bits of 1mm copper and soldered them to the back of the copper ring to relace the broken off pins.
Fixed.
And I forgot to take photos...
Dave