TIMING NOT ADVANCING WHEN VACUUM IS APPLIED TO THE DISTRIBUTOR VACUMM CAN

almost sounds like the advance cam is frozen in mechanical also, easy check with the engine off see if you can turn the rotor a bit by hand and if not the advance plate is rusted to the distridutor shaft, there is a felt under the rotor that should get a few drops of oil on occasion, I see so many distributors frozen up from lack of oil when I rebuild them, other than that if you see the plate moving no idea.