Record the setting that gives trouble
Write down every dial position for a suspect reading, including decades set to zero. State whether the result changes each time that setting is selected or only after the box has been in use. Keep any readings already taken with the identity of the measuring instrument and the connection arrangement. This helps distinguish a problem associated with one switch from a result affected by the complete measurement setup.
Keep the box and its connections identifiable
Include a photograph of the terminals, model plate and any damaged control. Say whether the box is normally used with two or four leads and whether a case or guard terminal is part of that arrangement. List adapters separately. A loose binding post and an unstable selected resistance need different work, even when both first appear as a changing display on the connected meter.
Agree on parts before replacing a decade
A repair estimate should identify the affected switch, resistor section or terminal and the proposed work. Availability of a suitable part depends on the model. Give RTS the approval contact and any limit on assessment charges before work begins. For a reference box with a long calibration history, request that the pre-repair condition and any replaced component are recorded against its serial number.
Choose the checks needed on return
List the individual decades and combinations used in your procedures. Ask how the zero-setting contribution will be recorded; it can matter when the selected resistance is small. A repaired switch should not return to reference duty solely because the display appears steady. Agree the resistance points, connections and reporting requirements for calibration after the approved work. The applicable CC-4643 measurement entry must be matched to those values and conditions.
Book around the reference bench
Tell us when the box can leave the bench and who will review the returned results. For an IMT Sohna unit, include the works address and receiving contact. If several sites share the reference, nominate one owner and one return destination so the next user receives both the box and its revised records.