Hi, I recently bought a Cardone part # 30-2808 distributor for 1957 and later block. I hooked a vacuum hose to the advance diaphragm to check
operation before installing. (I'm replacing my 1955 load-a-metic distributor). The advance arm from vacuum can would not move even though the advance 
plate in the distributor is free. I provided as much suction as possible using my mouth. I removed the diaphragm from distributor and again tried to actuate the arm while sucking on the vacuum hose. I couldn't get it to budge. Its seems as if there is a very tight spring under the diaphragm and it takes a huge amount of 
pressure to overcome. Does this distributor require some centrifugal advance to kick in before the vacuum will pull the diaphragm / arm ?? Anybody with experience with this distributor care to chime in? Thanks in advance,  Brett

1955 tbird