Keep hands out
Stop and isolate the unit through the normal accessible means. Do not reach into the chamber or run it again to create a recording.
Describe the event
Mention what was happening just before the noise and whether drainage or starting also changed. An engineer can assess an obstruction enquiry without assuming internal parts are damaged.
A useful distinction
Keep any known dropped item in the account even if it seems too small to matter. An engineer can assess its relevance; there is no need to retrieve it by hand or continue grinding to clear it.