These are common problems that can easily be corrected.
A nozzle dripping or not spraying can be caused by improper pressure setting. If there is no pressure, that could be a clogged filter or bad check valves.
First make sure that the aluminum filter attached to the end of the large pick-up valve is clean and free of all debris and the disc in the end of the large valve is not stuck closed. You can check this by pushing it with a pen while you have the filter off.
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