The Tv reception is Very Strong Signal Strength at your location.
Do Not use any type or kind of signal amplifier.
Attics Are Not a reception friendly environment and Never Will Be a reception friendly environment.
Reasons ,
Multi-path reflections , signals bouncing all around.
Absorbing blocking Tv reception.
Move the antenna to above the roof in such a manner that the roof and building are not , obstructing , impeding , blocking , reception in the directions of , North East , North West , West , South West.
Digital Broadcast Tv Tuners can develop -Digital Glitches- that are not cleared out with simple channel scans.
Do Double Rescan ,
www.wchstv.com/DoubleReScanAlert.pdf