In the restaurant industry stuff breaks ALL the time. Ideally you can call someone to fix things but if you have a vested interest in your kitchen or the operation as a whole you should know how to fix as many things as you can yourself, or at least be able to identify what the problem really is. Half because you need to get busted equipment functional again, and half because if you can figure it out yourself you don’t have to pay someone else hundreds of dollars to figure it out for you.