Many thanks for the info Bruce, the picture of the G68 with the 'Meridian' PSU was taken from your site, mine has the type shown in the G61, so not as old as I feared.
I was part of Intel tech support for Europe back in the days when repair meant chip level, not FRU, so hopefully I won't have any issues with dismantling and reassembling the backplane. Since posting the above I've read enough to think updating the SMPS to an LPSU is also a worthwhile upgrade.
Going back to the issue that caused me to take the top off in the first place, I'm really not impressed with the quality of the front panel switches; but at least that is a trivial fix
