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Anyone know why or what's causing there to be chemicals in my solenoid (? relief valve? I believe it's called???)? It is happening on 3 of the chemicals but not on my other ones

So I've got a a soft touch automatic tunnel carwash, and unfortunately the mechanic & data guys hardly did anything right and unfortunately one of the issues is my chemical setup. I've for the most part figured out most of it but the 3 issues I'm dealing with are one of the chemicals aren't even...