Not my MK3 this time which has an alternator but a friend's car with dynamo. Not charging. Checked dynamo uninstalled and worked as a motor from a battery. Installed and F and D bridged got voltage of 16v when engine running. When connected to regulator, nothing. Connected to regulator with F and d bridged it the charged for a while with ignition light going out but then stopped. Any ideas what to check next? thanks