[dmfdmf]

RCH7 is 174-180 MHz, have you tried an FM block? Run an FM Fool report for your location and see if you have any hot FM stations nearby broadcasting around 88 to 90MHz which could be interfering. As others have mentioned you are in a great spot for reception and the amp could be making things worse. Custom tuned antenna is a good idea to see if you can get anything.

I just took another look at your TV Fool report. Look at how high RCH2 is, the power is -10.3 dBm and broadcasting at 54-60 MHz. I am no RF expert but could the 3rd harmonic 3x60=180MHz be knocking out RCH7? That would be my guess. I have a radio station in my area that is at -9.9 dBm and it wrecks all my other FM stations across the band. I had to install a notch filter. I am not sure how you could test this.

Edit: Try this; Buy a Pico Macom HLSJ VHF Band High-Low Antenna Separator-Combiner (HLSJ) and plug your antenna into the VHF-Hi port, cap the VHF-Lo port with a 75 Ohm Terminator and run the LINE port to your TV. I'd re-zero your tuner and then scan with this in the path. This should knock down RCH2.