Hi Anthoni,
My father had a very similar problem, in that at the beginning he was able to get all the FTV channels on his old Panasonic 30 model. Then all of the sudden he lost his channels and got the infamous "no satellite signal being received" for no apparent reason.
At first I thought that the wind must have moved the dish, but on the satellite signal page I was getting all soughts of readings from the standard OK 002 72d4” to a load of others signals, but the strange thing was that when I did managed to get the standard signal, I got a “sat signal of 0” and “sat strengh of 100%” . Anyway after a month of being on the roof moving the dish with my mother shouting from below, I decided to try my receiver on his system.
When I tried I managed to get all the channels on my box without a problem so I tried and put his box back on, and we still got the infamous "no satellite signal being received".
So to make sure that it wasn't the Panasonic box, I tried his box on my system at my home, and it worked... mind you it took awhile to load up.
So the answer was the LNB resistance. For some reason my fathers machine worked perfectly well with an LNB of .7db for over a year, mind you it came and went, then it didn't and when we change the LNB to lower resistence of a .3db it worked again.
Now because CH 4 has a weaker signal than the other channels (ie. its the first to go in bad weather). It could be that you LNB on you Panasonic 30 might has need a lower resistance.
It’s just a thought.
Tony