It sounds like a problem with the controller board, not the inverter
board.
I would suggest you resolder all connections on this board, even the
solder-through holes where possible. These are usually multi-layer
boards and sometimes have inter-layer connection failures.

You might also look for a small 8-pin IC that begins with 24L or 24LC.
Many monitors store their setting in these flash eeproms. Sometines,
replacing one with a blank eeprom will fix the problem.

Phillips will probably not sell you parts for these monitors. You might
check EBay to try and locate a broken monitor.

Hope this helps...
John