coldlight sourceRemedy: Replacebearing;removal ofthe back cover,installation ofthegasketinbetweenthebracketand the bearing;investigationshaftor adjust theconcentricityofthe two axes;coldlight sourcewith due emphasis onloosetapetight;fillingcleanbutter, butteraccountedforabout60%ofthebearinggap;tocleartheobstructionofthebalancehole.coldlight sourcereasons:bearingdamage;rolling bearingorbrackettocoverthegap is too small;coldlight sourcebentshaftortwoaxesofdifferentheart;tapetoo tight;short of oiloroilybad;balanceplug the holeontheimpeller, the impellerlostbalance,increasing thethrustto one side.