So, I've tried 12.4 with the same result. I've managed to install clean 7.4 and it is ok. I've upgraded it to 8.4, ok. Then I've upgraded it to 9.3 the "CAM timeout" appear but system was booted after several retries, but booting was quite slow.
Were all of those from CDs?
I've tried to upgrade to 10.4 and it failed: CAM status: Timeout, Error 5, Retries exhausted and all these stuff in a loop...
Yes, it was too long jump between 9.3 and 10.4, will try to start with clean install 9.0...
Have you tried with USB i386 memsticks for these later releases? Or only CDs?
The CAM Status messages I tend to associate with CDs, but maybe that's not all.
If it were me, I'd be trying the [edit:]
If that boots and installs you can easily freebsd-update to 12.4 - then to 13.x by 2024.
Otherwise maybe it's time to move on; even my venerable T23 died aged 20, 2 years ago. I still mourn! <&^}=