This little wonder of British technology has lived on my 1938 Ariel as long as I've had it. Its does everything a dynamo should except generate electricity. Sometimes it does, more often it doesn't. I've stripped it, cleaned it, fiddled with it - still the same result - sometimes charging, sometimes not.
Some years ago I bought a spare dynamo, but still stuck with this one. Imagine my amusement when at long last I swapped the dynamos to find that the spare is in perfect working order, knocking out the amps like no-ones business. Of course this will only be the case during daylight.... Joe Lucas - Prince of Darkness.