N_Cook wrote:

Another maybe relevant factor. The IEC socket was rivetted to the pcb and
very firm but the section that is chassis mounted had much smaller diameter
screws than I would normally expect. Although star washers under the nuts
they undid easily. Maybe that due to the heating but also could be due to
normal inserting of cord into socket straining the pcb solder connections
over years of use/stowage. Would also explain why no obvious bad solder on
the ground pin as that is mechanically more remote by another half inch of
conductor compared to the active conductor lengths.

Look for the basics instead of pontificating. That's where it'll be. Getting on
for 40 yrs experience tells me that.

Graham