The latest battery piece is used to repair the typical corroded contacts in HP41c calculators. By far this is the most typical repair need in these calculators.
Some years ago, Diego Diaz created a foldable, adhesive circuit that could be used instead of the original cicuit. Initially, you would peel off the original circuit, remove the plastic rivets with a X-acto knife, and paste the new circuit once pre-folded. This was a fantastic solution!
This gave fantastic results - for a while. The adhesive, while strong, would give after several months of use - sometimes up to a couple of years. No matter how it pasted and pre-folded it, after a year of use the adhesive would fail and the outer part of the circuits would peel off. Good for your own calculator, but not good for somebody else's file.
So we set to find a permanent solution.
After some thinking, we addressed these failures. We decided to fix both sides with screws, with a total of 8 of them. We use also two 3D printed pieces to fix these circuit ends:
On the right you can see an exploded picture of the part before adding the circuit. This makes sure that it will never peel off! It has also tighter measures than the original, and gets secured by its shape too. We still recommend to put the back ports when closing the calculator, since it pushes the module in place.