Reinstall the pump and try spinning it backwards with a drill motor to see if it pumps that way. It sounds like your so-called rebuilder needs to try again. Is there a warranty?
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!