Jeez! This is turning out to be impossible. Last Wednesday, I called Comcast in Tallahassee to get 3D turned on. They told me I needed a new set-top box so I got one. I cannot get this box to even tune to the 2 channels. If you punch in 790, it goes to 801; channel down goes to 785. 3 hours talking to the CS rep here in Tallahassee got me "The channels are only active when there is content and so you can't tune to them; they will appear when there is content" On Thursday, I went to E-CARE web chat and was told flatly that Tallahassee does not have 3D, sorry, go away. Calling the 1-800 tech number gets me, yes, there is 3D and your account correctly shows you having it. No answer why I can't tune to it. E-mail tech help gets me a lot of boilerplate but no help; finally, they schedule a truck roll for next Monday. (ESPN3D shows no content after Sunday) Calling the 877 number for Comcast 3D problems listed earlier in this thread gets me: "No I don't think a truck roll will solve this, I will start a ticket and you should hear back within 72 hours.
Sigh, I just want Comcast 3D.
I can get the 5 min X-games demo in 3D and it works.