OK guys, no more false alarms. The test car is up and running after I replaced the chassis. I finally took my LC+ BN NW2 out of the box and got it going too. I'm ready to take this rig for a spin.
The short test run revealed readings in the 30 - 40 range, and as always when I put my hand near the antenna, the readings jump by about 7 - 10 points. I still wish I could pinpoint what I did to this section to cause the signal level to drop to these unacceptable levels, as it used to work fairly well.
The next logical step is to run the car through some of the areas with known good signal, including the small helix and the upper deck, to determine what an adequate reading is on my layout.