I s it really in order to use machine downtime during corrective maintenance in a technician appraisal?

Thanks Willys for the invitation

well, when the machine get down during operation, and the corrective maintenance has to be followed for preventing the machine from shutting off again, that time the technical procedures should be executed following the manufacturer troubleshooting procedures, understanding the fault and the cause of it, , and working on preventing  it from happening again, at least the same fault, and getting the machine back to work and operation safely,

so answering your question, you have to be sure about what caused the machine fault, and not just guess, so take your time, specify the reason of the fault, Fix it, and prevent it from happening again, then operate the machine and get it back to work again