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Slopes are generally dealt with careful timing, and not watering any longer than it takes for runoff to appear. If runoff appears before the soil has received enough water, then you have to "cycle and soak" with repeat waterings separated by a time period for the water to soak in.
Don't know what kind of controller you have (metal pegs?), maybe time for an upgrade that will easily allow more options.
You can get adjustable heads that will go less than 180 degrees.
Wet boots says you can just get new pegs. If that works I would stick with it and save some $$.
Hunter has a good selection of controllers. Basic up to advanced. Check their site. I assume you have low voltage wire to the valves?