CTX P973 19 in. Flat Panel LCD Monitor: Won't power-up

Over a period of many months my CTX monitor has progressively got worse and now it no longer powers-up. Please help identify any possible faulty componant. The 3 stages of the simptoms are as follows :-
Stage-1
My CTX P972L monitor started showing tearing (interference type)lines over the full screen when pressing the Power-On button but soon cleared and full video became present and stable until the next switch on.
Stage-2
The problem got worse in that when the tearing lines dissapeared I would have a blank screen and no video signal also the power button became inoperative and locked in the On position (blue LED on all the time)and I couldn't switch it off. To resolve this I had to remove the power plug then replace it. The power button would then work fine and no tearing (until next time on power-up).
Stage-3
Now the monitor wont power-up at all (no LED lights on the power button, blue or amber) however, on removing the power plug the blue LED lights momentarily. Similarly the blue LED lights up momentarily when re-inserting the power plug. But the power-on button no longer lights up when pressed and the monitor remains totally dead.

Please can anyone suggest a possible componant/s that could be the culprit (a specific Capacitor maybe ?). I am reasonably familiar with PCBs and their componants but very rusty on fault finding especially without a circuit diagram. So techspeak wont frighten me and your expertise would be greatly appreciated to point me in the right direction and help me find this fault.
Best regards, Bob