Where I worked, we would often get requests for spares from the past. As is common, some very early products will last a long time, before people get pressures from accountants to cut costs, once some experience has been got.
I once got a letter from some obscure place in the ex-colonies, asking for a spare terminal bushing* for a thing that I'd never heard of. Some searching found the details of the component. It was clear that there would not be 'one lying about somewhere' and, it would be hugely expensive to attempt to make one, plus the design required materials that would have been illegal many years before, so it would require a completely new design.
I informed the potential customer of the ridiculous price that we would require, should we agree to have a go at making something that might work.
They got quite shirty about us not having one on the shelf, even after I pointed out that they had bought it before my father was born.
* This sort of thing.