Start with the pattern
Describe what the dryer does—not the part an internet search named.
A dryer contains several moving systems: the drum and its supports, a drive belt and tensioning system, a motor, a blower, seals or glides, and model-specific bearings and fasteners. Clothing hardware, the exhaust connection, the floor, and the neighboring washer can also create or amplify sound.
Listen for the closest category: rattling or ticking; a repeating thump; squealing or chirping; scraping or grinding; buzzing or humming; or a vibration that shakes the cabinet. Note whether the sound begins immediately, changes as the dryer warms, appears only with a heavy load, follows every drum revolution, or occurs when the burner or blower starts.
Those details narrow the inspection. They do not prove which component failed. A squeal can arise from several different rotating parts, while a coin or clothing fastener can imitate an internal failure. Replacing the “usual” part without locating the sound can waste money.
Capture an intermittent sound: record a short video from a safe distance, then photograph the model label. Do not hold the phone behind a running dryer, reach into the drum, or move a gas-connected machine.