You don't explain what mfr antenna you have, mesh/solid or how old...
Does this happen on all satellites all the time???
Or just the few satellites you watch the most??
The trend for Satellite Tv has been to squeeze more & more satellites
in orbit closer together
(2 degrees or so between them) and some of the older antennas just
don't have a good enough design to discern from
the desired satellite to the next satellite over (east or west). Gets
especially problematic with more & more digital transmissions
that your analog receiver cannot see. Anyway, since it was working fine
and then just "crapped out" as you say, I'd be looking to check the
antenna for imperfections, check the feed assembly to make sure it's
really focused, and check that the probe moves smoothly inside the
feedhorn when you switch from Horizontal to Vertical Polarization
(change channels). Sometimes your motor can go sour and strat to
"drag".

Good Luck,

Bill