Well, it's not the 'screen'. Perhaps some
of the video ram is bad, or the
character generator.
Yes, I figured that - that's why I asked if replacement chips are still
available (I'm not overly technical, but I understand that lots of old
computers used a fair number of off-the-shelf ICs that are still available
today).
My question about screen replacements was unrelated to the actual problem
with the PET - I was thinking long-term, just in case the screen ever dies.
It would be irritating (to put it mildly!) if the only source of
replacements was other PETs, because there aren't too many in the UK.
Gareth