check if the the wiper arms are tight on the splined stud that they swing on. my BMW wiper blade
, had this problem,stripped splines in the wiper arm...the return of the wipers is caused by a cam within the wiper motor. once the wipe starts, the cam should keep the motor on until you get to the
end of the wipe. If the motor stops immediately when you release the switch, the cam could be shot. If the motor continues for awhile, then
stops with the arms in the wrong place, the arms are not in synchronize with the cam.