I had another go at the cables in the PB145 tonight, paying particular attention to the display cable that connects to the inverter board, adjacent to the keyboard cables exposed when you take the top off the machine. These were simply disconnected & carefully reseated/ reconnected, but there is still no obvious improvement.

The one thing that seems to make the flickering die down is simply leaving the machine (and screen) on; after 4-5 mins or so, it's pretty good. This suggests to me that either the electrical exercise of the old components has some effect, or (more likely) that solder joints are moving with physical warming.

I am not going to worry about it too much, as I have powerbooks and such aplenty, but when I get a free evening, I'll take the whole thing apart and check the visible solder joints etc. in the key areas of concern as suggested. I like to keep the old machines running as best I can, and strangely enough, I rather like this old gal. Fabulous keyboard for its day - far better than the one on the PB150, oddly enough, though they look identical.

Thanks for all the help.