I had my doubts that it would be so simple a fix as the symptoms lead me to believe a serious blockage was the problem and the joker valve was replaced last summer. Yet when i removed he old valve it was calcified and badly deformed. The pump worked freely with the valve removed and works freely now with a new valve. Accordingly, need it or not, I'm going to replace the valve every spring--they are cheap and as we know, nothing is quite as bad as head problems on a warm day in July.