Both monitors are approx 5 years old, and are 'budget' monitors (good
picture, FST tube etc, but not name brand).

Budget monitors that are five years old. That actually explains a lot.

A lot of so-called budget monitors are crap with cheap parts and shoddy build
with questionable engineering.

One such example is a monitor where its mainboard is so placed that it would
warp when the monitor was resting on it's swivel base. This would eventually
cause a whole load of cold solder joints, some which could cause a catastrophic
failure of the monitor itself.

Buy something from a respectable name brand next time. They may be more
expensive, but they will certainly last for a much longer time. I would
recommend Sony monitors over any others if considering CRT displays.
Viewsonic, NEC, and Panasonic aren't bad choices, though. - Reinhart