Started off great, then after 6 weeks, stopped working

I have a above ground pool, about 35' wide and 5 feet deep. It gets a lot of dust and leaves at the bottom and this picked them all up really well the first 6 weeks. Then all of a sudden after 6 weeks it will not switch to the setting of large pool, it will only stay on the small pool setting. Spent a lot of money on it. Really disappointing.

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