Thanks for the suggestions folks. Well I ordered a new vacuum advance and when it showed up it was different from the one on it. The difference was the collar that goes around the distributor was straight where as the one on it before was at a 45 degree angle, so this means that the collar adjustment screw and nut get in the way of the bolt that holds the distributor down, which in turn could round off the hold down bolt. Any ideas? is this new vacuum advance ok to use or should I look for one like what was on it. Also does the collar (C clamp type thing) really need to be there even?