Belt and roller wear in a dryer shows up first as sound and motion, and only later as a drum that stops. Walk through the checks below once in a while, and write down what you hear and see.
The sound at startup
Start the dryer empty and listen. A steady hum from the motor is normal. A hum that comes with slapping or squealing at the drum, or a rhythmic thump as the drum begins to turn, deserves a note. Log the time and the load. Repeat the check the next time you run the machine.
The drum that slows or drags
Watch the drum while it runs. Note whether it turns unevenly, stops and restarts, or sounds louder on one side. Look at the belt only if the manual says it is safe to do so and the machine is unplugged. Look for a belt that is glazed, cracked, or sitting off its groove.
Idlers and rollers
Idler pulleys and support rollers wear over time. Listen for a grinding or a whine that changes with the speed of the drum. With the power off, press each roller by hand and feel for roughness or play. Write down which side the noise comes from.
Drying time as a signal
Note any change in drying time for a load of the same size. A drum that slips or drags can run longer without the clothes coming out dry, so your times will drift. That drift belongs in the log beside the sound.
What to do with the log
Keep the notes in one place, each entry with its day. When the same signs repeat across more than one check, bring the log to whoever services the machine and ask them to read the belt, idlers, and rollers against it. Ask what each part is and whether the repair makes sense given how old the machine is.
The dryer's typical service life and planning guidance are on the Clothes Dryer page.