A customer had a brand new dishwasher installed and a couple of days after installation the customer ran it only to find the tub would fill but would not drain! They called the installer and they wouldn't come out for three weeks. So they contacted me.

Drain pump seems to be running as I could hear it but the water still wouldn't drain.

I suspected the air gap was plugged so I pulled it off and noticed a LOT of crud inside. It took a bit of time as I ran a wire through to dislodge both orifices and kept flushing with water. It was primarily clogged from the "dishwasher drain" side as opposed to the "disposal hose" side. There was a lot of gunk, a broken toothpick, and some sludge. The broken toothpick did a good job acting as a beaver dam, and was a pain to get out. But I got everything removed.

How in the world is gunk getting into the air gap if the dishwasher has a filter? Perhaps accumulation or gunk fell into the dishwasher while the filter was removed?

Regardless, it's fixed and works great. But I do want to replace with a better air gap that might be easier to clean in the future. This one looked like a cheap Danco. Any good recommendations?

as strict as Massachusetts plumbing code is, a dishwasher air gap is not required.
we just simply run the DW drain hose as high as possible under the countertop.
no one has died from the bubonic plague because there is no air gap.
cabeesh ?

Lucky you, @Packy! I live in looney land California. Can't wait to move out next year!!!!!!!!!!!!!!

I was just re-thinking this. Could the back flow from the disposal have caused debris to get into the air gap?

Into the line from the air gap, but not into the "feed" line.