So, if the copper from the CO is okay and the inside wiring is fine, but the DSL modem won't sync even when it's directly connected to the NID... what's left that could be at fault? That's right, the DSL modem itself. I pushed a little on the subject and the tech ordered a replacement for me. Happily the unit was under warranty so it was a free replacement. Overnight shipping was paid courtesy of SpeakEasy, which impressed me a great deal.
The new unit arrived today. Since I'm sick at home for the second day in a row I was able to unpack it immediately upon delivery. I called up the tech line again and, to the surprise of all involved, as soon as I was picked up from the hold queue I got the same fellow I've been working with for the past few days. I plugged the modem in at the NID and got signal, though the poor tech couldn't pull any stats from the DSLAM due to an internal issue -- frustrating, but something we could deal with. I moved the modem into my computer room, plugged everything back in and was pleased to see the DSL light start flashing as the modem trained with the DSLAM. A minute later it was passing traffic and I could ping sites on the Internet once more.
So, for the last two hours and forty-seven minutes I've been online from home. I think replacing the modem may have actually been the fix for the issue (all signs pointed to it being at fault but I still had nightmarish visions of needing a truck roll from the ILEC so I could get somebody with an Agilent DSL test unit on the premises to confirm good signal). To be on the safe side I'm going to shake the circuit down for the next day by punishing it as much as I can -- streaming audio, a bunch of downloads, you name it. If it stays up and functional I'll ship back the old modem and gradually re-add devices (TiVo, cordless phone, 2600 sets) to make sure I can accurately pin any problems down should a new issue arise.
With that solved I can now move onto the next big annoyance: USB 2.0 on my machine. Expect a Lazyweb post about it.
You fight the sunday crawling