I overpaid for this... IBM Model M ashtray, for the lack of a better word. I looked at pictures of the internal assembly online, and I think there're missing springs? For example, I can't press the upper half of the enter key because there's just no spring there, not even blue placeholders. I can't exactly buy new springs from Unicomp as the shipping is so prohibitively expensive that I could buy a IBM Model M from someone else.
Some early Ms have extra wire stabilizers on some longer keys. I think I've seen it on the numpad plus and enter on like '86 and '87 models, but it disappeared on later models. I think this might have corresponded with using more plug inserts.