I'n not sure why John is suggesting the all-channel antenna. If you are getting 7, 9, 11, and 13, then you have a fine antenna. The issue is local interference of some sort, very likely reflections that add up in the wrong way for KCBS's frequency. Don't forget that KCBS is actually using a UHF channel per the real channel column in your TVFool report.
A very nice resource that helps explain the physics behind the situation in a way that you can use is
this site. You seem to have a clear shot at the towers as far as terrain goes (all the paths are LOS, or line-of-sight.) What the prediction model can't tell is what buildings and trees nearby may be doing.