Firtsly many thanks to all of those who participated in this thread.
Originally the picture on this TV was wavy and distorted. I replaced a few marginal electrolityc capacitors and the picture looked almost normal but was always grainy on all channels.
After checking I/Cs etc. I decided to remove the tuner (big shitty job) and checked for opens etc. I did find a connection which looked as if it had a bad contact and resoldered it back properly. Tuner put back and TV turned on and to my disbelief the picture on all channels was still grainy.
I was furious and in anger I started to fiddle with any internal controls I could put my finger to. Offcourse nothing improved except that I messed up the colours etc.
So the TV had its backpanel replaced and put on the floor for disposal or eventually parts.(at least to get back all those caps I had replaced).
Later on that day I thought I will try the "one in a million" possibility; I took the TV inside the house and connected to the house antenna. I spent the next couple of hours contemplating how I was going to take this F... thing apart again to fix up the messed up colours caused by me in anger; why? because the picture on all channels was no longer grainy.
Note: in my garage I use a different antenna which has been always been okai but for some reason it did not please this HDTV television. The TV is now fully functional. Cheers AL