Very true! What is really important for tuning that people tend not to commonly have at home are small files.If I may comment on the tool kit shown in the beginning of this thread. Some members seem to feel it's expensive. I must say I differ
with the comment "expensive". I personally feel the price of the kit is an insult to the intelligence a perspective customer. The tools in
the kit can be substituted with common tools & pieces we all have.
Read here ---
I would recommend something like thie file set available from Carini. You can also buy scratchers and larger files separately from them, and you will also need some type of wetstone (grinding stone) to sharpen the tip of scratchers....
But of course what you need by far the most is *skill* and that only comes over time. Often when I get an accordion in for tuning (from friends only) they will not have had any maintenance for over a decade, and likely about 10 high reeds or so will not play at all, and have been treated badly by the last repairer to touch them... and then it requires the right tools and skill to get all of them to sound properly again (without replacing any)... but it took me years to get to that point.