This model has a single RF input. I'm not using anything other than the coax input for the OTA testing.
What I've been doing is running the Auto-Program at 5 degree intervals around 114 degrees in three different locations, one outside a second floor window, and two up in the attic. I've swapped the coax-cable as well. I guess it's looking more and more like the tuner itself might be defective, which is a shame since everything else about the TV is excellent.
Are there any commercially available tools for checking the tuner?