hotpoint first edtion 1000, wont complete a cycle, filter unit?

My washer wont complete a cycle and has stopped spinning completly but the belt is fine. I thought it was maybe the timer knob. I took the top off once more and tried it without it on and there is a small silver cylinder with 'filter unit' wrote on it wich is buzzing quite loudly does this need to be replaced or is it possibly something else????