Just got one of these, superficially not in great condition - the keyboard cable insulation is disintegrating for a start. But the PSU works and the system tries to boot. Opened it up and it's spotless inside. Has the orange plasma screen. Also has a boot problem I am looking into.

But there is another problem - the plasma screen has two horizontal lines [ie. orange lines] running across it [and some dark mark in the middle at the top - not sure if this gives a vertical dark line and the machine is put away right now]. Wondering if these lines could be caused by something simple that could be fixed? Anybody know? Have seen it suggested that some contacts might need cleaning - is that likely to be true?