IT'S FIXED!

I thought I'd give a brief feedback on what fixed this issue. The fix boiled down to simply reseating the 40 pin ribbon connector on the P3's I/O board. Works good now.

I'd like to publicly give a big shout out to Alan, N1AL, for his thoughts and guidance as I troubleshot this issue. We exchanged several emails off-thread that were very helpful in guiding me to the root cause. Alan designed the P3 hardware and firmware, so I knew I was in good hands. Thanks Alan! 

73,
Chuck
W9BIK