Also, I have had a set of points where one of the contact points had come slightly loose. Very hard to spot that, worth checking, and the plastic post which isolates the current of the contacts set also can come loose,(that happened on my ts 150) it looks ok, but when the points open and the contacts return spring put load on that little post (where the nut is what attaches to the alloy bridge to the condenser) it moves, that can affect the timing/ignition also. Hope this is of some use, to you or maybe any one else suffering with ignition troubles.
Ruud.