@roland I'll answer you on this thread so it's on topic.
No, we had cleaners to sweep up back then! It was the "4000 type" selectors which used to shake bits off. STC SE50 I think was the manufacturers name for them. They were re engineered versions of the traditional "2000 type" which turned out to be less reliable and the Post Office went back to the original design.
I don't have a lot of spare selectors or banks, most everything I have is mounted on the racks. And I gave a lot of switches to a friend who was building a rack. I have some uniselectors. Depends what you're after?
Jon