Pictures of the PB2 with the epoxy blob removed.  Interesting... if you examine the square solder pad directly below the R15 label, then more closely at the lower right corner of the pad, there is a brown line running to the right, toward the label R25.  There are scratches on the PB2 that I made removing the blob, but this scratch (dig actually, the pictures don't do the same justice a stereo microscope does) I am certain I didn't make.  I found a similar break in one of the traces on a PB1 and assumed I did that when removing the goop.  Q: Could the traces have been purposely damaged (at the factory) to disable a preexisting feature or communication path?  Maybe time to pull out the old soldering iron again....