We have ordered the production of custom screws to replace the original in your HP41c -should any of them be lost or broken.
In particular, we have decided to change the lower ones for the longer version that was used by HP to repair the calculators when they came back to their service desks. The advantage of these longer scres is that they "bite" deeper in the lower screw posts, saving some calculators where the original screw posts were lightly damaged and did not make enough pressure.
Pressure is not an issue in the newer half-nut machines (those with rounded corners in the screen), but it is of utmost importance in those full nut units that didn't use nuts to screw the main processor to the keyboard, but were pressed to it by means of a couple of stands in the back side. The pressure was produced by the lower screws, and they had to "bite" into the posts, which required be tensioned. This is eased by the longer screws.
In the picture besides you can see a extended lower screw and a higher screw.
We will also provide adhesive silicone rubber feet for the calculator. We're thinking to have a full set of lower screws and all 4 feet as a pack. Upper screws seldom are lost, and those you really need are the lower posts.