Orfices are under the fitting on valve stack that the hoses hook to. They can be removed with allen wrench. They can unscrew on there own and if they did you may just find a ball of brass under fitting. We have just bronzed fitting tight and drilled the proper size hole when we have one that has come out. The size was either .040" or .052". Check your orfices and if they are in there and still operates faster than you want you will want to modifiy to a smaller hole to get it slowed down.
