Greetings, the vacuum advance in my '67 has died and I'm trying to remove and replace it--I see in the shop book that it has two screws anchoring it in place, one at its inner end and another on the outer end---presumably the same one also holding the condenser in place? I've taken them both out but the unit still won't release from the distributor plate...am I missing something here? Is there another screw or fastener in there somewhere I have to get at? I don't want to force it too hard but do they sometimes get "frozen" in place and require a bit of persuasion to come out? Thanks for any tips, Jim.