Tub was refilled about a few days ago. Temperature hasn't gone above
99... pump sounded awful...
Four valves removed later... boom!
Water all over the back yard.
Seems there was an air bubble which had built up behind a valve. It
was keeping water flow from occurring through out the system. When
released water shot out of the tub like a fountain.
Release the air bubble, and everything works.
I love mechanical stuff :)