On Sat, 29 Jul 2017 14:45:34 -0700 (PDT), wrote:

snip

if it's only 1 bad diode try running it without it, on half load or less it should be ok.

Now I've got them all out it seems to be two bad diodes but one was
reading strange things so maybe died fully as I got it out?

2x400v diodes in series should do as replacements temporarily.

Ok, I can give that a go tomorrow ... especially as I have so many
1N4004's. ;-)

Cheers, T i m