This actually answers a question I was making myself about this sense of reliability of old equipment, In my experience its a nightmare to service and maintain old equipment. One of my first job was in the manufacturing (machining) industry, it was a small operation and it needed old computers with old software that controlled some old (~6 years back then) but very expensive quality control and milling equipment; those were all old PC's, with old ISA buses, old and insanely expensive RAM (that eventually failed), I eventually convinced my boss to replace those things with cheap assembled PC's, we had to buy PCI expansion cards for all the serial and parallel ports that the measuring table seemed to need but it worked out just fine.
There was a kind of sentiment that those machines were somewhat magical and no new PC's would ever be able to connect successfully and run the aging software (the equipment was second hand, out of support, software update was in the thousand dollar range), they depended on them so the things had to be reliable, right? If we add regulation to this attachment that management has with old 'working' equipment we get the nightmare that it is to deal with medical equipment and (now I know) nuclear facility equipment.