The model is the starting point for identification
Record manufacturer, model, variant and serial number. Two configurations in one family may have different equipment. Include the part reference and a label photograph taken without unnecessary disassembly.
Separate symptoms from diagnosis
Describe what the robot does rather than assuming a specific module is faulty. A communication error does not prove controller failure. If diagnostics exist, include their findings and scope.
Ask for written confirmation
Confirmation should refer to the exact part and your configuration. Agree kit contents, installation, calibration and testing requirements. “Suitable for humanoids” is not enough for a purchasing decision.
Compare the cost of the complete result
Add diagnostics, transport, labour and downtime to the component price. Ask how long the quote remains valid and what happens if additional items are required for compatibility.