Identify the stopper
Say whether the original operating stopper is present and whether it was replaced or damaged. Describe the usual movement and response without forcing it.
Model before parts
An engineer can check whether the enquiry concerns an operating accessory, interlock or appliance fault. Similar-looking stoppers are not automatically compatible, and safety interlocks should never be bypassed.
A useful distinction
A stopper that still blocks water may no longer perform its operating function correctly. State both results separately so the enquiry distinguishes its role as a plug from its role in starting the disposer.