Are there any gotchas or tips when replacing a vacuum advance unit? I'm figuring all I need to do is mark the dizzy before removal, then try to put it back in the way it was before. I'm thinking if it gets me close enough so that it runs I should be alright. Anything else I should be thinking of? For some reason I remember reading about someone else having trouble getting the distributor back in during re-installation... Thanks in advance!