Remove drain pipe and check entry hole into the u bend under the sink as if this is blocked will prevent a GOOD PUMP from emptying, If blocked clear with stiff piece of wire This blockage will occur again due to the small size of the hole,a better way to drain is to install stand pipe 1and a half inch diameter to the outside drain, If hole in u bend clear pump is suspect partly blocked or seized if impeller won't rotate clean out pump lastly check and clean out sump hose filter this ensures there is NO BLOCKAGE to prevent machine from emptying
wirecutterman, December 2007