I have a Hoover SpinScrub SteamVac and it's leaking water out of the attachment hose spray nozzle. Even after I release the button that causes it to spray, it continues leaking a steady stream.

SOURCE: Hoover Steamvac hose won't spray water

SOLUTION#1 If the attachment wont spray water, the white plastic nozzle tip may be clogged. Take the brush attachment off, remove the two screws from the gray retaining cover (BE CAREFUL THE WHITE TIP UNDER THE BLACK PLASTIC TRIGGER MECHANISM IS SPRING LOADED and WILL GO FLYING). The trigger mechanism can be taken apart by lifting the black part off (may have to slide it back slightly), remove the spring from the white plastic valve insert, then take a flat screw driver and carefully pry the two white pieces apart and blow out both ends. You may have to find a hair size piece of wire to push threw it to clear it. The whole process is really simple once you take it apart and see how it works. Putting it together is in reverse order. The white piece will only go in to the black part one way and with the spring on you need to push it through the hole and the trigger part hooks on, slide it back on to the hose, then while holding it all, and put the gray retaining cover back on. Sounds more difficult than it really is. If your not mechanically inclined take some pictures as your taking it apart to refer to.
Solution#2 If the nozzle and trigger are clear, with the trigger assembly off the hose, plug the hose into the shampooer and turn it on (if the hose inside the suction hose is clear you should start seeing water flowing out the hose. If not run a piece of wire through that hose to unclog it. If its still not flowing then the Pump on the unit needs to be replaced.
Solution #3Cost Around $20 with shipping online. Google your make and model, and upholstery attachemnt pump. Mine was called AP4561692 (43582018) PUMP ASSM, from http://www.appliancepartspros.com/. (there real good about the live chat and helping you find the part).There are Youtube videos on taking apart the shampooer, which is pretty easy. The one place that might give you problems after you get down to taking the pump off, there is only one screw holding but there is on the bottom side of the pump a black bump that clips in to the base of the shampooer and you need to stick a screw driver from the bottom up and pry the base one way and pull the pump the other to unhook it.