You probably already know this, but... My sense is that a collector of classic computers has to be able to diagnose and repair at the component level - get in there with an oscilloscope and a set of prints (creating the latter, if need be), and find the busted chip/transistor. It's like collecting old cars - if you collect old cars, you have to be able to work on them (or like Jay Leno, be rich and hire someone else who can - although given that Jay worked at an auto dealer 'back in the day', he apparently does know a fair amount). Which isn't going to help much with this particular problem, maybe some of the other replies will help. Noel