I don't know if this will help you, but if you search for "Nicolet 4904 operation manual", you will find the 4094 manual -- and yes, the model number is wrong on the website. Joe seems to have collected quite a bit of historical data on this and other fun things, and programs that will run on it, and so on and so forth.
My only other comment is that... generally speaking, with older equipment, it's very often the capacitors that go bad, and power rails and such go bad internally, and things stop working in various ways. I suppose just sitting there long enough could put it over the edge. The fix is often pretty easy, for those with the intestinal fortitude -- replace the bad capacitors.