The repair kit for the battery bay of the HP41c (flex kit) is having good acceptance among users, but it is important to know several things upfront to avoid failing:
The first consideration is that this is a DIY undertaking. Some users have been put off when receiving the adhesive sheet - they expected to receive the assembled thing that you can see in the picture.
While it is not difficult, and it is quite short to do, don’t try to do it if you have always failed when DiY’ing! You will need to have some steady handling when adhering the film to the substrate. It is not difficult, but forget it if you suffer from Parkinson!
The second: you need to follow through the instructions of the installation manual, that you can find in the article. Please read them through.
Please make sure that you do good bends. Spend your time there and you will be rewarded with a good fit. Specially important are the negative bends, that will ensure adherence in the difficult-to-reach cavities.
Avoid the desire to use a sharp object to push the film to reach the bottom of the corners. You should have done better bends instead. The danger with the sharp object is that you can easily break one copper line - it has happened to me once and you will only notice it when you connect the module in the affected hole. I have it affecting module 4 in my HP41CL, but I am using only modules 1 and 2 (time and infrared, if you wanted to know). As the machine is a HP41CL, I don’t need anything else - and I still have bay three for the HP-IL when I need connection to my multimeter.
There is a recommendation to heat it at low temperature in an oven to get a better long term fit. It is a little more effort, but try it too.
The flex film is not immune to rusting. Don’t leave the machine with the batteries if you’re not using it - just like any other HP41c! The only good thing in that case is that, now, you know how to repair it!!