rent a gasoline powered unit. I did so, found that it had enough power to peel strips of wood out of the treated lumber deck-dialed back, it cleaned it up fine. Then purchased an electric unit. Much less power, but enough to clean the deck-until it blew an o-ring. The wand was made of mattel grade plastic fittings, with metal to plastic bearing surfaces- The wand/hose/spray head are pretty much unrepairable, and are not compatible with currently available replacement items:replacement requires separate purchase of wand, hose, and nozzle heads for a total cost that exceeds that of the original device. Renting the unit as needed will cost more, eventually, but will save time and vexation.