On Thu, 18 Feb 2016 06:10:08 +0000, MJC wrote:

Wow! When riffling through mixed resistors, long before that many I get
a powerful urge to pick one at random and paint it in the right
colours...

LOL! I like your thinking. Actually when I returned to the task today and
fished out another tub of caps, the very first one came out at 535pF -
close enough to 560pF IMV - and didn't go up in smoke when I put 270VAC
across it. Neither did its capacitance change afterwards, so I've got
myself a replacement part at last. Funny how these things eventually work
themselves out.