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 ****ty 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