Eratic , unstable , reception with a antenna in the attic is to be expected.
As always , trees and tree leaves , plants and plant leaves , Will produce degraded reception.
Some channels will be ok and some channels will not , this is the Norm.
For better reception install the HD7694P antenna above the peak of the roof in such a manner that the roof and building are not , impeding , obstructing , blocking , reception in the directions of , South , South East , North West.
Aim the antenna at about 163 degree magnetic compass direction.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.html.
The higher the antenna is , the better the reception will be.
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Digital Broadcast Tv Tuners can develop -Digital Glithes- that are not cleared out with simple channel scans.
Do Double Rescan ,
http://www.wchstv.com/DoubleReScanAlert.pdf.
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