There are three "hard " wires coming from the stator and soldered to a connector block to which the harness is connected.Check the “hard” wire connections for a dry joint.I’ve had this happen on a Spada and a BMW R80.You end up with only two phases working and a charging light that stays on with the engine running.The block in question is either next to, or mounted on the stator.I can’t remember which.I’ve long since gone back to models with the more reliable 300 watt dynamo system.Good luck 
I’ve just noticed that I’m described as a “Non MGCGB” member. Lies…all lies.I am a member,honest.
That happens as it is not automatic to upgrade your status to member. Contact the forum officer to get it changed.
Best wishes
He’s changed the stator, but engine heat and heat inside the alternator cover cooks the plastic insulation on the loom leads, so I think this could be a wiring loom problem. This is why you should really use the type of alt. cover with the spacer ring behind it, which provides air cooling vents.
This is a T5 so will have the spacer ring fitted as standard.
I’m stumped with this one. If Keith can’t fix it, then it must be a real odd one.
If he wasn’t nearly 3 hours away, I’d go and take a look!
it does have the spacer,every component has been changed,the bike was re wired by ferret over a year ago
This one’s got me stumped.
The odd thing was when Shaun said it got up to 13.5V when he pushed down on the brushes, makes me think it must be something to do with them connecting onto the rotor.
But you would have thought swapping the stator would have cured that.
bugging the crap out of me,never had a bike beat me before
Not reading back to see if you changed them , but have the brush springs got enough tension on them ?
brand new and the holder
Yea ! thought that idea was a bit simple mate but worth a try.
Good luck, bloody electrics! work of the devil 
It looks like you have 2 faults at once.
This means you need a qualified electrician to sort it out.
That means someone who can spell electrician without reverting to google.
Daft question time - memory may be playing tricks on me but i seem to remember the brushes have leads that have to be soldered, i.e. can’t just rely on the springs making contact. (?)
every single wire is soldered
If you can get hold of a copy of Guzziology there’s a great guide to resting the Tonti era charging system. It breaks the testing down to give the thumbs up/down to individual components and the looms.
I keep a copy under the seat of the bike when I’m doing longer runs.
Should you struggle with getting the information PM me your email address and I’ll sort something out.
All the best
Steve
Thanks for the offer, but I have a copy… 
Just too Gormless to read it, the story so far…
After swapping out everything that could possibly make electric, I had the tank off to see about the wires, found the connector under the tank, that carries the wires from the alternator, wasn’t loose. BUT, it came apart VERY easily… 
Just before I took it to bits, I put a multi meter on it, and in the Omega setting, it was showing all OK. I unplugged the connector anyway, and re-plugged it in, good and proper like. Fired the bike up, and I’m SURE I got a 13.5v reading on me digital meter, can’t be sure, cos it seems the spark plugs, or some such, is making the thing jump about with the engine running. The volt meter on the bike, that usually works great, was still showing a lose of electric… 
So sod it, I’ll be using the bike till it breaks down with no electric, then I’ll get it over to Corsa, and let Paul play with it. It’s not only got Moto Bradley done, it’s got me well and truly done in…
It’s taking a while due to a bike rally in Belgium last weekend, and me bloody car breaking down, guess what with…? YES, electrics, a broken wire that took a professional 7hrs to find… 
I’m surprised there’s a connector under the tank - on the early models the 3 yellow wires go directly between alternator and rectifier, with no breaks. By the sounds of it I’d want to bypass that lot with 3 new wires.
The bike has been rewired in the past so it’s probably not standard any more.
I think i’d go back to Ferret as he re-wired it
Chilly, Ferret did the wires 18 months ago, and at £400 a day, I’ll be buggered if I’m getting him back…