Use your bathroom scales - or borrow some - weigh yourself holding the TV set and then weigh yourself without the TV - do the math - I would guess about 10kg or 22lbs give or take a little.
You have made a change to your TV setup - following this some things that used to work no longer work - it might be the cange you made that caused the problem.
Might it be that the "missing" channels were coming to you via the cable TV box?
A most interesting and challenging question.
Peccavi
April 2010