[Hampshire] Recurrent Hardware Problem

Hello, all!

Quite a while ago, I had a problem with a machine which suddenly wouldn't
start. After several attempts it started and ran normally and then would,
again, refuse to start. On power-up, the fan would sometimes 'kick' and
then.... nothing. Very occasionally, it would start and run normally.

I checked everything I could think of, replaced the power supply and on/off
switch (etc.) but the same problem continued.

I raised a question on this forum, but got no answers. I never did resolve
it and eventually cannibalised the machine for spares.

I've just encountered another machine (a completely different make) which is
displaying identical symptoms, so I'm moved to have another try.

Does anyone have any suggestions?

Chris.