I was about to send my 15+ year old SR-80s back for a re-build, but waited a bit too long. I wanted to take them on a trip, no time to round-trip to Grado. So, I took the opportunity to do a little tweaking and repair myself.
The two issues were the cord (dried out, hard, and bad connection at one ear), and the pads, which I'd changed to the yellow Sennheiser HD-414 pads years ago, and were now in very bad shape, what with the yellow getting dirty etc.
I replaced the original Grado cord with a bit of Canare Star Quad L-4E6S cable I had around the shop, splitting the two pairs and putting heat-shrink tubing over them. http://www.canare.com/ProductItemDisplay.aspx?productItemID=53 The L-4E6S is 21ga wire, a bit heavier than the original cables.
Next I ordered the real Grado pads (black, "comfy" style) for $10 at Audio Adviser. They arrived in two days.
The results of both changes, apart from getting a reliable right ear back, was pretty shocking. First, the mid-range "honk" the phones had developed, and I though I was imagining, vanished with the cord change. I do drive them from a headphone amp with very low output Z, so lowering the cord resistance a bit probably did the trick.
I would never have expected that changing the pads would make that big a difference! The top end is back again, and there is a renewed sense of space and dimension that had slowly been slipping away with aging pads. I wish now I'd not tossed the old pads before making a few measurements. I think they had become acoustically slightly opaque in their old age, the open cell foam was turning into closed cell foam.
Anyway, my SR-80s are back in action, and I can highly recommend the pad change. Not sure if the Sennheisers were wrong to begin with or just crushed and old, but the new pads made the big difference. The cord change less so. Of course, with all of that going against them, plugging the old phones pre repair into an iPod was just plain disappointing. But now, iPod line out to the amp, to the new cord and pads...Ah. That's the sound I remember buying them for!
A foot note: I recently auditioned a new pair of SR-80i at a store. The played a CD player through an amp of some kind, didn't get the name, but it had two outputs and two volume controls. The new SR-80i phones left me cold. Not the same at all. They were blarey and upper mid heavy. Actually, nothing in the store sounded good, must have been the amp. But I'm happy with my old SR-80s again.
Change your pads once a year, when the cord breaks, get something better, and drive them from a good high current low Z amp. Sweet.