Whirlpool Dishwasher won't drain

Our dishwasher doesn’t drain…, I’ve checked the hose to the garbage disposal, inspected the checkvalve, inspected the impeller and found no problems. When you hit the Cancel/Drain button it runs but doesn’t drain. I didn’t take the pump assembly apart any farther than the impeller, do I need too or do you think it’s the pump?

My cook top cracked I ordered a new cook top but need instructions as to how to install it. Please help. :slight_smile:

This should help
http://www.servicematters.com/maytag_library/docs/16010161.pdf