All outside coax is/are suspect of being bad.
All outside connections and connectors are suspect of being bad.
And All other coax and connections and connectors through out the system are suspect of being bad.
As a Test to prove reception , connect a New continues length of coax that has the Compression Type Connectors on the ends of the coax , not the old crimp type connectors on the ends of the coax.
Run the New continues length of coax through a open door or window direct to 1 Tv , No splitters , No couplers , No nothing , just direct to 1 Tv.
What is reception now??
Recommend aim antenna at about 224 degree magnetic compass direction.
Digital Tv's can develop - Digital Glitches - that are not cleared out with simple channel scans.
Do Double Rescan ,
http://www.wchstv.com/DoubleReScanAlert.pdf.
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Be sure and Disconnect and Remove All passive and active cable tv devices.
If any type or kind of active cable delivered service , be it , cable tv , cable internet , cable phone , the active cable service must be on a seperate coax that is not connected to the antenna system.
Yes the coaxes that were connected to the cable system can be used for the antenna system.
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Trees and tree leaves , plants and plant leaves , have a Negative effect on broadcast Tv reception.
Multi-path reflections bouncing off the trees/plants and tree/plants leaves.
Trees and tree leaves , plants and plant leaves , absorb and block Tv reception.