Quote Originally Posted by drshinn View Post
Also, when you shut off the pool you can hear a whistle coming out of the basket.
Sounds like you are hearing a suction leak, leak.

Besides a bad O-ring, other possibilities include

+ a cracked pump body;

+ a dirty or damaged O-ring groove;

+ dirty or damaged threads for the lid, that prevent full engagement of the lid.

More info on suction leaks here: http://pool9.net/suction/