It's not as cliched as you think. I like the idea of a factory producing magic, and I like the idea of the protagonists having to fix their mistakes.
I do have a question, though: this is obviously fantasy, but if you were K, the head of a massive corporation that provides magic to the world, would you hire a fourteen-year-old bumblehead? How is this kid qualified to work at whatever job she has, and wouldn't K have hired more responsible people for the job? Some managers fully scrutinize applicants before hiring them--as I can attest to. More decisions than we'd all like to think are made before the interview even happens, simply because managers need the best people for the job.
The above isn't really a critique--just something to think about. What you've got here is your concept--the back of your book. Unique magic systems attract me, so the back of your book at least drew me in. I want to see how the world is affected while magic is unusable, what people say and do to the people responsible when they find out, what the temporary replacement is, how the Magic Gear is fixed, etc.
Your concept also implies a more whimsical than realistic fantasy--in realistic fantasy, the damage caused by a collapsing magic system would be catastrophic and the girls responsible would be severely punished, perhaps even put to death if the loss of magic killed anyone (for example, a heavy object held up by magic falling on someone's head).
It's difficult to critique concepts. Post more, like a script or something, and then you'll get more helpful critiques.