I've had a pair of Grado SR60 headphones for about two years now, and I
guess due to repeated usage/abuse on my part, the bass now buzzes when it
drops esp. low. It used to be a small problem in one ear, but it is now
noticeable in both ears. The problem is not noticeable at very low volumes,
but after turning up the player to a reasonable (not exceptionally loud)
volume, the distortion can be heard. The major problem with the warrantee,
if I'm still covered under any: I have lost my receipt. Are there any
shops that perform service on these models? TIA for any help guys

Ben