thanks for all the possible solutions ., as its working well with the old mechanical regulator ive decided to leave it as it is for the time being and try it on my SR when the top end is back on ,I have received a reply from Dynamo Regulators Ltd who will check it for a tenner plus postage each way but they are pretty convinced it is more than likely down to " dirty " brushes... very reluctant to throw more money away ! cheers , Phil . ps. just wondering if there is any easy way to check it off the bike ?