I have a Adafruit 16-Channel 12-bit PWM/Servo HAT (P2327) that is installed on a RPi3. I followed Adafruits directions and it worked perfectly on the Pi with Raspian Jessie. I then decided to upgrade to the latest Raspian Stretch. Everything seemed to install fine. I went to run the test python program "Servo_Example.py" which worked fine on Jessie and nothing happens. No errors, no movement. Any ideas would be appreciated.