What direction does your balcony face? Do you have a line of sight towards both La Jolla and towards Mt San Miguel? Your TVFool plot indicates that your UHF signals should be easy but channels 8 & 10 will definitely not be easy due to terrain blockage. However, the plot cannot know about trees and buildings that may be in the signal path which effectively tosses any forecast out the window.
Do NOT aim the front of the antenna towards La Jolla (northwest), aim it the opposite direction towards Mt San Miguel (southeast). The antenna is bi-directional on VHF but sharply more directional off the front (by 15-20 dB) for UHF. If you aim it the opposite way from where the UHF signals originate, you sacrifice up to 99% (20 dB) of the possible signal on UHF.
On both UHF and VHF, you have an effective beamwidth of 65-70° so small changes of less than 30-40° in the aiming direction usually have little effect.
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If the antenna is "looking" through one or more buildings you're going to loose at least half that signal.
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You're too optimistic.
"Half" the signal is only 3 dB. A better estimate is anywhere from 10-40 dB (90.0 -99.99%) depending on the building's size, construction, distance, and the frequency of the desired signal.
Most new construction in the US must now be done with energy conservation measures included. Radiant barrier insulation is now common in sunny areas and signals do not penetrate it. Additionally, stucco, which usually has a metal screen backing, is the predominant exterior in Southern California and also blocks signals. If the signal path is indeed blocked by buildings, the only signal propagation method is a combination of diffraction and reflection resulting in very little signal power of very poor quality.
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I'd certainly also try moving the antenna up and down a few inches, as well as trying it at different locations on the balcony.
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An excellent tip, one that must always be remembered. The antenna user often has to search for the signals since they're not inclined to obey our wishes by being present in adequate strength and quality in the spot where we want our antenna to be placed.