Hi My Dynamo E3L On a 59 Norton ES2 is Not charging both the regulator and dynamo have just been rebuilt and are as new. I was thinking is there a clutch in the mag that drives the dynamo and could it be this thats is slipping and not allowing the dynanmo to spin up to speed?how can I check this fault? This is a whole new ball game as I was a 70s jap man and have converted to Brit!Thank you for help and time to reply Gaz in the dark

Presumably you have a pre-featherbed model, or you should have an alternator ! There is a slipping clutch which is to protect the fibre driving gear (which could of course be stripped). If you remove the dynamo cover band, you will at least be able to check if it is turning. I think it would be a good idea to get hold of a copy of a period workshop manual covering Lucas magdynos, because they set out quite nicely the various test procedures which are not that complicated and if you have a test meter then you are already a step ahead of most owners in the 1950s !

The clutch is slipping and as been sent for overhaul.