My recent aquisition, a rainbow backplate Model M with square label, got its screw mod. It was easier than I thought. After a trial run with a donor board I attacked the silver label. The board lost about 2/3rd of its rivets through its 33 years of use. It sounded very strange when I typed on it. So a mod was the only way of make it work again as it should.
I used Madhias guide (viewtopic.php?t=9169) as a reference. Other than he I used only 2,2*6,5mm flathead screws. I would not wait until my ordered bolts and nuts arrive. It was worth a try and it worked.
back plate de-riveted
interestingly the membrane is glued onto the back plate
tool time. About 60 holes have to be drilled. Before that I used a side cutter to remove the remains of the rivets
always block those holes where no spring has to be
a bunch of screws to be installed
pop back the keycaps
After everything was assembled I had to adjust some screws which were too tight. With screws too tight some of the wire stabilized keys stuck.
Two things I have to work out: The big ass enter does sound a little bit rattling when pressed. Unfortunately this Model M uses wire stabilizer rather than the insert ones all my other Ms do use. So I cannot change keys to test. The other one is the screws for the very bottom row. The screws would be to long and stick out on the upper side. I learned it the hard way on my first screw mod. I have to sources even shorter screws for this row. But even without them all seems to be okay.
Maybe I'll mod this board any further. A bluetooth mod would be awesome. Also some light blue Unicomp keycaps are on the way to me. I'll give it a semi industrial look.