You may want to check the waste tank shut off float wires/ connection. My machine (not a Chief) did the same thing in the past and that was the issue for me. Just something to look at and a easy fix. Good luck my friends.
I was only asking a question, because I'm looking at purchasing the sprayer myself. I've always flushed out my sprayers at the end of the day and have not had issues with any of the pumps.
Please don't be defensive.