The 3E also had common parts with the 1E/1A, the issue is, loading the generic and overlays on the 3E is.. special. It's special in part because the 3E as they show it, isnt a complete 3E, its a partial one, below the minimum equipment list.
The largest issue was replacing the pinch roller in the tape drives (last time I was there). That same drive was also used in the Dimension PBX, and some other gear. Also the rubber bands in the cartridges too.
The museum has a huge amount of spares in Parkway, and most semiconductors, even the weird shit AT&T used, are mostly replaceable.
But there is something true here - the SxS switch - everything can be made in a machine shop, same with the panel switch.
The durability of modern electronics is.. considerably better than old electronics.
Consider this, I have a 1989 Plymouth Acclaim, it has all of its original electronics, all of which more or less work - not only that, I can keep going out and buying spares for it, its a 33 year old car.
I think the restorability of old cars will be somewhat better than it might appear, because the supply chains exist to keep them alive in the long run.
Old computers are another issue, because the supply chains for long term maintainability just.. dont exist - so you're left looking for gray market spares in weird places, hoping you can find oddball parts that were often used in one off designs.
The largest issue was replacing the pinch roller in the tape drives (last time I was there). That same drive was also used in the Dimension PBX, and some other gear. Also the rubber bands in the cartridges too.
The museum has a huge amount of spares in Parkway, and most semiconductors, even the weird shit AT&T used, are mostly replaceable.
But there is something true here - the SxS switch - everything can be made in a machine shop, same with the panel switch.
It gets harder when it gets newer.