Thanks, Chad. No thought goes unchecked, and I appreciate any ideas. I can tell you that I did check DM and it's been OK. Much of the time is works fine, but then it sputters. So whether it's going bad or maybe needs to be reseated, it's pretty much narrowed down to a physical problem. To make things worse, it is not accessible in any easy way. The bottom chassis needs to come off and that it a pretty complex job. The bottom screws are easy, but there are some hidden ones around the CD/DVD drive (left side) and near the track pad (left-center front). For now, I've opted to pop in a 150-n USB micro. I will someday brave thre full disassembly so that I can replace the Realtek--likely with a dual 2.4/5 to take advantage of my router's second frequency.