[BILL]

The buffer takes the damaging arch out of the vibrator points, your power supply works about the same as the distributor,in the old cars vibrator=points, buffer= condencer, transformer= coil, to get your high voltage AC, then your 7Y4 rectifier converts it to high voltage DC for your "B" voltage , your buffer is C 19 on your schematic, looks like .015 mf , most are .006 mf, put in a 1600 volt one, most likely the buffer is leaking and was drawing too much current and burned up your vibrator, may have damaged your power transformer and even vibrator hash. Many times people would just change the vibrator and end up doing a lot damage to the radio, with a shorted buffer a transistor vibrator would last a few seconds .,BILL