Taffy, this unit that I'm pointing, it's a regulator/rectifier, and you also have another regulator.
It's like this because that unit it's connected to one of the yellows and it's powering the battery.
The other yellow is connected to one regulator only and it's used to power only the lights.
This is the original configuration, but you can make another arrangements.
Slangen, this is not a 3 phase regulator, because the bike has a single phase stator, only has 2 single phases.
What do you mean by broken stator ? usually that part of the stator don't break ?? and one of the yellows should have power enough to power the lights (70W)
Anyway, check values between the yellow and the blue to know if everything is ok, if values are ok should be the regulator.
But if you had one of the phases bad (one of the yellows), the one that is connected to lights, and the one that goes to batt in good condition, yes, you could disconnect the batt one and use it to the lights.