lost some hd channels but not all of them.

I have lost many of my hd channels, but not all of them.   Any one have any ideas why??  We have trimmed trees.  Satelite   110 is 99% with only 3 active transponders.  Satelite 119 is 98% with 11 active transponders.  Satelite 101 is 99% with 32 active transponders.  I am at a loss.This is so frustrating