No direct experience of this in a printer like yours, but it sounds like what happens a) when RAM is bad in one of the more expensive Postscript laserwriters like the LWPro 630, or B) when capacitors fail on the logic board of a Mac (i.e., the machine starts up but hangs).
You can't fix RAM without serious surgery and equipment, and there won't be much of it to fix anyway on a Quickdraw printer, but the "good news" is that there may well be bad capacitors by this stage. I would hope for B, and tear it down in order thus get the logic board out and clean it/ wash it, and then see what happens. You can't make matters much worse.
Disassembly of these more or less requires a service manual, if the machines are anything like the LW 4/600 at least, as otherwise you are likely to break the plastics. I had to take my 4/600 apart once to install the über-rare RAM chip, and I seem to recall that it was not especially easy to do, with much flexing of plastics at set points on the frame being required. Mind you, that was several years ago....
You can't fix RAM without serious surgery and equipment, and there won't be much of it to fix anyway on a Quickdraw printer, but the "good news" is that there may well be bad capacitors by this stage. I would hope for B, and tear it down in order thus get the logic board out and clean it/ wash it, and then see what happens. You can't make matters much worse.
Disassembly of these more or less requires a service manual, if the machines are anything like the LW 4/600 at least, as otherwise you are likely to break the plastics. I had to take my 4/600 apart once to install the über-rare RAM chip, and I seem to recall that it was not especially easy to do, with much flexing of plastics at set points on the frame being required. Mind you, that was several years ago....