> I would imagine WD40 would do more harm than good?
Yes. It dries out and leaves a sticky residue so it may be better for a
short time but will then be worse.
I don't know what was normally done/used but suspect its like the teletype
where you want a needle tipped oiler with a light oil and put a drop on
each of the moving locations. Some parts may also want a light grease.
If you can find a service manual for any related model it will give you
the general idea on how it should be lubricated.
Can't help with how it is operated.