How to fix an old HP41cx

[burkhard]

The 41 depends upon the lower two screws to clamp the top and bottom of the calculator together. But they play more than a structural role. That clamping force also establishes good electrical connection between the top and bottom via the "zebra connector". Google "HP41 zebra" without the quotes and you'll get a lot of hits including pictures to show you what I mean. Anyhow, if the screw posts (especially the lower ones, as the zebra connector sits right around these) are cracked or broken off, you won't be able to have sufficient clamping force and all sorts of gremlins ensue. The vast majority of the time, when a 41 is acting really flaky, it's because of that zebra connector and the main ultimate cause is broken/cracked screw posts which need to be repaired or replaced.

Let us know what you find.