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I'm trying to remember a short story in the science-fiction genre.
It is a story which features a society that revolved around teaching people to maintain spaceships, but in the distant past they had become cut off from the people who actually had the spaceships. This society continued to teach spaceship maintenance long after they knew why they were teaching it. All knowledge of how the knowledge was actually practical was lost.
At some point, one or more people with the maintenance knowledge are re-united with the society that actually has the spaceships - which are seriously out of repair because they lost the repair knowledge when they lost contact with the world that did the repairs.
I think the two societies then get together again, but I don't remember how it ended or much of the actual plot.
What is the name of this story?