I own a large number of Apple Keyboards, and my friends and family as well. Very often these Keyboards start to have the two common issues: either keys are stuck, or keys stop working entirely. I found this great answer from Allan to "Keyboard key stuck or not being recognized; how to fix", and he is mentioning these two facts, alongside some commentary.
As described on ifixit, the usual quick fix is canned air, but sometimes the problem sits deeper (crumbs, spill or swollen battery, as written in this ifixit answer). Some of you remember the teardown report for Apple wired keyboard on ifixit. I started to disassemble my existing non-working keyboards and researching the individual part numbers (I added them in the head-version of the ifixit report).
I am wondering if someone can point me to more detailed ways of identifying and fixing the problems, as i want to start repairing these keyboards (i have around 20 broken Apple keyboards alone).
Especially i would love to hear how to diagnose and potentially fix the "classic" situation of broken circuit paths.