Well my monitor failed and I called someone out to see if that was the problem rather than assume and rush out and buy a new one when the pc may have been at fault.
I was charged a ridiculous amount of money for a guy to come and give the monitor a bit of a shake and say it was knackered.
But he did say I could open it up myself and see if anything was loose.
Now I am a plug it in and press buttons kind of person but I unplugged, unscrewed the back and even I could see what was loose. So I pushed all the connections (not that many) home, screwed the back on and .... it worked.
And still does. I am using it now.