1st off you need 12 volts and a good ground. I've gone through 3 pumps and found that they dont like to sit idle. Lucky for me Bennett has a real good warranty program but for most the warranty is long gone.
Do you use a different switch? if yes then the diode may have gone bad. Banderlog, Rex Marine & Bergeron all make a better wiring setup to eliminate the diode. Its built in on most here is a pic below of Baderlogs version. I plan on getting one someday.
http://www.banderlog.com/products/po.../withLabel.jpg
Mine stuck at the beginning of this season and I tapped gently on the servos and they have worked great all summer.
No need to bleed the system It does it on its own.
Here is MJ Thomas email at Bennett
MJThomas@bennetttrimtabs.com He helped me out big time.