“The dishwasher pump is broken” is a diagnosis. “The cycle stopped after twelve minutes, water remained in the tub, and the display showed E24” is an observation. Start with the second kind of statement. Record the model, approximate age, exact symptom, last normal operation and any recent change. Do not run a damaged machine again just to improve your notes.
Use a three-column page: observed, possible explanation, evidence still needed. A drain problem might involve an obstruction, installation, a pump or a control. The symptom alone does not select a part. Put a question mark beside each explanation until a qualified diagnosis or a specific owner-manual instruction resolves it.
Practice with an existing symptom or a fictional example. Write the two questions a service provider would need answered, then price a diagnostic visit before ordering components. Your output is a one-page handoff, not a shopping cart.