http://www.dynamoregulatorconversions.com
He converted my Ducellier regulator and it is now fine. He also tested my dynamo and told me there was no need to convert to 12wv electrics. So far, no starting problems at all.
I did have trouble with the ammeter and when I plucked up courage to open up the dash (which was easier than expected) I found the contacts loose and dirty. Now all working well.
Good luck
Ian
Ian Stroud