OK, this is a bit of a pain, but try disconnecting the 270 ohm resistor and the positive terminal of the 220 uF capacitor from terminal 21 and then measure the DC voltage at terminal 21 the same way as before, red to 21, black to 12. That will help determine if the rectifiers are bad, or if they are working Ok and there is a short to ground in the circuit somewhere after the rectifiers.
By the way, I have had meters that worked OK on lower scales but didn't work on the highest voltage scale. If you had it set to a lower scale when you checked the battery you might want to measure that battery one more time on the 400V scale. It won't be as accurate, but you should see at least 1V.