Is my generator or regulator broken?

While flying my system voltage typically is 13.1-13.5V. I intermittently see drops down to 12.1-12.4V which last for several minutes, before the system recovers back to the original voltage. This is of course accompanied by the low power indicator lighting up. The recovery is not instantaneous it looks like the voltage uses a few seconds to climb up through intermediate values before it reaches the high target value.

I have been told that this can be caused by a broken wire on the stator. But since the voltage so clearly jumps up and down between the two intervals and remains there for significant time, to my ears this sounds more like a regulator issue. Could it perhaps be that the regulator gets overheated and stops doing its work? I have not seen any clear correlation between OAT and the voltage drop frequency. On the other hand, the 13.1V-13.5V range seems a bit low if the voltage is expected to be around 14V at high power settings, Indicating that default perhaps is in the generator after all.

I appreciate any insight you might have on this, I have not been able to glean from the manuals how an intermittent failure in the generator can affect the regulator output, or the failure modes of the regulator.