[morzh]

I think it is not crud. I exhibits zero cinductivity. After multiple attempts. Which to me means the contacts do not even touch.

With od Philco switches like 20/70/90/111 type bad contact is common but there is nevertheless a contact, and once it conducts, it self-heals.
This type has no contact whatsoever.

Buying a new working part is easier and with this situation the money saved is not worth the effort.