Grado headphones are known for producing high quality sound, but they can also produce a rattling, distorted noise known as the Grado grattle. The grattle happens when the diaphragm inside an earpiece creases, or when hair or other debris gets stuck in the earpiece. If your Grados show symptoms, try a few fixes before giving up on them.
Remove the foam pad around the earpiece, and use tweezers or your fingers to remove any hair or debris from the headphone speaker.
Gently blow into the grille side of the earpiece in an attempt to clear any remaining hair or debris.
Play bass-heavy music loudly for half an hour or so to fix a creased diaphragm or displace internal debris. Don't set the volume so loud that the sound distorts; this could damage your headphones.
To pull out the crease in the headphone's diaphragm, remove the foam pad from the earpiece, and very gently suck the speaker mesh with your mouth. You might hear a popping sound as the diaphragm returns to normal. Use a hair dryer about 2 inches away from the earpiece for 15 to 20 seconds to set the repaired diaphragm in position, so the crease does not recur.
You may need to repeat any of the steps or have your headphones professionally repaired if the rattling sound returns. Grado offers a one-year limited warranty on all its products. Consider contacting the company and getting your headphones repaired or replaced if they're under warranty.
Blowing or sucking on the speakers too hard may do permanent damage. Proceed carefully.