After re-reading this thread from the top, I'm leaning heavily in favor of a new antenna.  The Winegard HD7694P or it's larger variants come to mind.  Not because you need the gain but as ADTech says, 
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					Originally Posted by  ADTech
					 
				 
				While the towers are in the same relative location,  the signal doesn't always behave the way we want it to.  You are likely  experiencing what I call "frequency-specific multi-path".  That usually  means that you are getting an errant reflection off something on or near  your line of sight that is interfering with the "primary" signal in a  destructive nature. 
 
The solution is to either try a more directional antenna (hoping to  reject the reflection) or to move the antenna to a different location  (up, down, left right) and try again, hoping that the new location is  not bedeviled by the original reflection or a new one. 
			
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 I'd like to see you get more than ten years of service from an antenna but clearly the coax in the weather needed to be replaced and the existing antenna has some damage.
I know this is redundant, but... Don't use any sort of amplifier.