Lady and me have been together for over 30 years, Lucas dynamo on a series C, I fitted a JG unit in 1974, it has been fine until now, the dynamo has finally spilled its guts & I have bought a Alton - Looks great but the Lucas 'mo had a tapered spacer, the parts list shows a shim for the miller unit, the Alton fits too snug to the primary chain, I have no knowledge of miller dynamos, do I need PD19 or am I better of using a large dia. o ring to effect a seal? any help welcome. THANKS.