Just one last thing to show how misleading things can be.
A good friend called me and said he could get EVERY satellite from 42e to 30w EXCEPT 5e (then called sirius) of course I laughed at him and said impossible but as he was only about 5 miles from me I drove out to his place (a farm).
I checked what he was saying and he was right no 5e, as his motorized dish was on a wall about 1mtr off the ground I took a look.
All connections were watertight and the dish moved smoothly and clearly stopped at about where I thought 5e ought to be.
Looking very closely I noticed a very fine crack in the LNB casing, a hair line crack easily overlooked so I changed the LNB, hey presto 5e good and strong solid signal and quality readings and tons of channels.
Now to this day I dont understand why it was only 5e that was effected BUT it's true, rain was seeping through the crack and preventing the LNB working correctly.