pump does not work on hotpoint aquarius df61 ?

Hi, my dishwasher does not fully empty, it seems that the pump does discharge but very slowly and does not shift enough water in its alloted time , thus accumulating , a deeper puddle in the bottom with each wash cycle . I have checked for debris around the pump impeller, have removed the rubber non return flap and blown down the wastepipe backwards and all seems ok . Presumably the pump is not rotating at full speed (Motor duff?). Anyway having read a few posts on the matter , it seems that a new pump is a - very expensive and b - hard to work on . so what is the opinion of my idea of fitting a std washing machine drain pump into the discharge pipe from the dishwasher as low as i can get it , and connecting it to the origional pumps power supply to it ?