When I was looking for a part, I noticed the subject:
"ALTON DYNAMO PROBLEMS" on www.petersclassicbikeparts.nl.

As I am using one of them, and it works OK for me,
Except for some strange gear grinding noise (Low tone)
That was not there when I was using the dynamo..
It can be best heard when using the ex' valve lifter to shut down the motor.
It stomps with an unpleasant rough grrrrr in the background...
Anyway, I know that Ian does not like them, and there were discussions
Regarding "Alton" in the past, so, this is what in Peter's site:

"ALTON DYNAMO PROBLEMS"

"WHY WE DON'T SELL ALTON STUFF ANYMORE"

"Their alternators look nice, it was a good idea to make an alternator in the shape of a Lucas dynamo but...
Over the years that we sold them we had many problems and Alton was extremely slow to solve them, while I could apologize with my customers.
Since 2009 we wait for a compensation for a batch of 12 Altons with a built in problem, that I sent back to France. Mr Hamon has not bothered to sort out the problems, nor pay me my money back. That's why I regret ever getting involved with Alton."

FYI,
Noam.

email (option): noam10@gmail.com

Correction:

Peter's classic bike parts,
Not Pete's as I typed by mistake..

email (option): noam10@gmail.com

I bought one from Paul Goff and fitted it to my BSA M33. Up to present I have done 2000 trouble free miles, but time will tell I suppose.. I'm going to fit one to my M20 too..

email (option): ian@integsci.com

Hi Ian,

Yes, as I said I also do not have any operational problems,
And I also had some 2000 miles on it.

Charge is good, start to charge on low RPM.
I have 2 loud 12V horns, and good lights.

The only bad thing is this that annoying grinding noise.
Before I fitted the "Alton", the bike idled as smooth as butter,
And now there is an added noise.

I wonder what was wrong with the 12 units that Peter sent back..
Maybe it is that noise?..
I can best describe the sounds- like you would rotate a worn bearing slowly..

Noam.

email (option): noam10@gmail.com