A friend found a suitable power supply. So the laptop is up and running again.
I haven't done any more than hunt around on the 'net, in forums and news groups, and read Slackbook
and more from Absolute BSD
. All very useful stuff but I haven't found an answer that satisfies my need to understand what's going on.
I could simply ask on the forums what files I need to edit and how, but that wouldn't be entirely satisfactory unless it came with an explanation of what's going on.