Many times on Delco dist with the advance weights in the top like on chev-----------the shaft doesn't get lubed and gets sticky--------can be stuck in the far advance and not start-backing it down will start but not rev, etc-remove rotor and twist the part that the springs weights are on and see if it rotates on shaft smooth/easy---------If you have to take it apart IIRC you must remove dist drive gear on bottom of dist and remove dist shaft so the advance unit can be taken off and cleaned up--- you might try some penetrating oil from the top but if you get too much oil in there it will be slung around in the cap causing miss fire-