I'm sure RadioHolland, Sperry or Sam Electronics would renew some old models or flawed units a few times per year. They might be worthless for them, but of great value for someone who wants to make his own SCU
You just need to know the right person on the right place.
Before the ShipSim era, our rate of turn pilot for steering on the rivers died due to a coffee spill. The whole unit had to be replaced. Never thought of asking if i could have it though, if only you knew everything on forehand..