Hello Gus,
WXXI-TV is listed as Tropo on your tvfool report. You will never get reliable reception of that channel that is 108 miles away, with a Noise Margin (NM) of -21.4 dB and a signal power of -112.3 dBm.
The reason you get it sometimes is because of favorable tropospheric propagation:
https://www.google.com/search?q=tropospheric+propagation&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US
fficial&client=firefox-a&channel=sb
http://www.dxinfocentre.com/tropo.html
To be reliable a signal must have a NM of no less than zero. WXXI is way below zero.
To be reliable a signal must have a signal power of more than about -83 dBm. WXXI is much weaker than that.
I don't go much by antenna distance ratings, but your antenna is rated at 40 miles for that channel. You would need an antenna with a gain of 21.4 dB to bring it up to NM zero----very hard to find. That is intrinsic antenna gain, not preamp gain.