Easy,
They will go bad after a while, and some times they just pop out of place. Go to your local supplier and ask for o-rings.
They come in two sizes for the gun connects and the hose. I think they are 3/8 on the hose and 1/4 on the gun tip. You can change them with a small screw driver. Pull out the old one and replace it with a new one.
While you are replacing make sure you stick it down on the little ledge inside the connecter.
Stay dry replace your o-rings today
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Dan Flynn
Flynn Service Pro
www.powerwash.net
708/715-4206