Dishwasher won't drain

I have a GE model GLD4200L00BB..

It won’t drain, all the time. I sometimes put one of those cleaner thingies in (blue, long and skinny, fits between the racks) and it will sometimes drain. Now i have just water…

Sometimes the water is UGLY. Sometimes the water is clean…

I really don’t want to buy a new dishwasher… Help me Obi Wan… you’re my only hope.

Crusty.

Oh… I"m going to remove the machine from the wall.. so If I gotta flip it over… it’s fine.

OK. Here’s what I know now. I’ve pulled out the washer, pulled the drain motor out, no crud. The little spiffy flapper is not even chipped, yukky, or, well, it is smelly. I know the inlet valve is working because I get nice clean water when I clean out all the junky water.

I know the pump for the jets is working becuase I gotta clean crud from the little holes periodicly.

Tell me doctor… It’s starting to look like the controller, isn’t it…

Crusty.