As a Test of reception install a Channel Master CM4228HD antenna aimed at about 319 degree magnetic compass direction.
Here is how to aim antennas ,
http://www.kyes.com/antenna/pointing/pointing.
It can help to bend the mast pipe so that the CM4228HD antenna is 'looking' at the top of the mountain ridge the direction of Mt. Wilson.
Install a Winegard , LNA-200 'Boost' XT amplifier.
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Digital tuners can develop - Digital Glitches - thaqt are not cleared out with simple channel scans.
Do Double Rescan ,
http://www.wchstv.com/DoubleReScanAlert.pdf