Thank you for the hint.
What I did so far, is reseting the NV RAM and gone through the "Manual Adjustment" up to, and including the power adjustment.
However, when I exit the test mode and restart in "normal" mode, the LCD displays "ERROR"
So, refering to the thread quoted below, I was assuming USB_PAtchWriter was needed.
I will retry the fulll adjustment/alignement procedure to its completion, and hopefully that should resolve it then...