I had 2 sat C LNBs die on me last year...one in August and the replacement in November. I have the Protection Plan so I called DirecTV when the second one died in November and kindly asked that they give me a the new triple LNB dish. At the time they said that they couldn't replace the dish for free, just the sat C LNB again. But they said that if the tech that they sent out determined that the problem was with the dish, then they could replace the dish for free.
When the tech came out to replace the sat C LNB, I told him that this would be my 3rd sat C LNB in 5 months. He told me that he hated the sat C LNBs and said that the new triple LNB dish was much better. I told him what DirecTV said about the free replacement dish, so he said "Well, the problem is with the dish" and called DirecTV to tell them that. They needed to schedule another service call since the tech didn't have a triple LNB dish with him. He actually didn't have a sat C LNB either...they didn't tell him what the problem was that he was coming out to fix even after I told DirecTV to make sure to note the I has having a problem with the sat C LNB since the LAST time I had the problem they sent out a tech without a replacement sat C LNB.
Bottom line...it's best to get the new triple LNB dish rather than mess with replacing the sat C LNB.
Good luck.
Marc