[aside, thanks for the various ‘white screen of death’ answers on the forum, just sorted out the CMOS battery on my T-80]
Shifting my iDR32 around I heard something fairly heavy rattling around inside. Never a good sign.
Opened it up and found a loose choke. Looks like it came from position L7 on the PSU board.
Some years ago the phantom power failed across the board. I found workarounds which became permanent as these things often do and the board is working fine with no other problems.
Is the L7 choke likely to be the source of my phantom power issue? - I don’t really want to mess about too much when things are working well enough otherwise.