i got so fed up of mine doing that, so i decided to open it up few days ago.
i took the entire unit out... surprisingly it was only 2 screws and 4 clips...
at the back of the unit, once its out, there is 2 connectors, one big white one with about 16 pins, and an earth plug.
took the unit into the house, and started to clean it.... at the back of the unit there is a "box" that is attached using 4 tiny screws, it may not be the most descriptive sentence written, but once you look behind the screen you will know what i mean by "box".
take that box off and you will notice 3 connectors underneath, 2 plug style connecters, bit like the power of the old floppy drives in PC's and one ribbon.
i took them all off and sprayed WD40 onto it.
Becareful with the ribbon, as the black holder is very stiff and have very small clips, i broke the right side of the clip but it still holds, taped over it just incase.
plug them all back in again, put the "box" back on, reconnected it all... since then its worked everytime. im not holding my breathe though, as there seems to be no sure way of getting it to work 100%
but im feeling confident. *touches wood*
in terms of diffculty, its not at all. i suggest you give it a bash
good luck