Dishawasher would not drain

I removed screws in trim, kick panel and counter top. Turned off breaker at electric box, Dishwasher slid out easily. diconnected water line; so i could slide entire unit out of cabinet. Laid unit on side and cleaned up the water that leaked out.
Removed the pump with nutdriver, replaced pump and reconnected electric, drain hose and screws.
Replaced unit into cabinet, connected water and turned on electric. no leaks, ran machine in rinse cycle, at time for pump I could hear and feel it was running, but no water. Evidently my original problem was the "air gap" device. I repaced it $4 at Home Depot and it works like a champ.
In hind site, the air gap probably ruined the old pump, so you might want to consider changing it out whenever you change the pump.