From time to time there are posts here about the Facit
N4000 paper
tape punch/reader unit. The one that looks like a Facit 4070 with a
tape reader on the front (in fact the punch mechanism is much the same
as that in the 4070).
I have reverse-engineered mine and traced out the schematics. Of
course it's one of my hand-drawn ones but I think it's mostly legible.
If anyone wants it I am happy to send out a copy (but as ever I'd
rather send it out once and have somebody else pass it on)
-tony