Hi Marcus, thanks, but I'm well aware of the belt conversion. Ted has already passed the dynamo as fit ( fitted new bearings though). I've fitted an AGM battery ( 13AH) which I believe has sorted the initial problem, plus the old, but not very old, battery wasn't much good, didn't hold a charge for long when fully loaded and left on the bench for a few days even! I'm considering a belt conversion though as I believe its a bit quieter than the chain that needs changing anyway.
ps. Ted has retired, but his son ( a chip off the old block) has taken over the reins and does a good job with a reasonably quick turn around ( for me anyway) I've known them for years and have had numerous dynamos and mags refurbished by them with never a problem. Unfortunately, they never answer the phone though.
1960 Matchless G12
1958 AJS 18s