Vibrator Buffer Capacitors

Any of you who work on the old tube car radios know that when you replace a vibrator, you need to also replace the buffer capacitor.  Vibrators, (Mechanical) are getting expensive and hard to find.
 A bad buffer cap will cause excessive current to go through the points on a vibrator and burn up the contacts much quicker than normal. You really can't test a buffer cap properly with most cap checkers, as they can't put 1200v-1600v-2KV on them.

The "Approved" way to replace a buffer cap is to replace it with a NEW one of the ORIGINAL VALUE CAPACITOR. One is supposed to replace the cap, then check the current draw, then try a different value and check the current draw. This is even more important if you can't get the exact original value and have to sub in say a .0047  or .0056 in place of a .005.
                   Use the value that results in the LEAST current draw.

 (Hmmm... I smell another substitution box project coming up...)

Do not try to replace the buffer with a normal 630V cap. It will fail due to the voltage spikes from the points opening and closing .

I once worked (For a VERY brief time) for a guy who would throw in whatever value cap he had as a buffer capacitor. When I told him he needed to use the correct value, he told me  "It will work". (Yeah, it will, until the vibrator rapidly fails and a COMPETENT tech puts in the correct value buffer cap. Hence the brief time working for him. Not in my ethical realm).