Plumbing – How to find replacement dishwasher parts

I have had my Bosch dishwasher for about a year using the same setup you contemplate, so I'm familiar with the exact drain connector you have on the dishwasher hose. On mine, there was something of a taper between the 1/2 and 3/4 section and being rather flexible rubber, and I had no difficulty stretching the 1/2 section of the fitting to fit on the 5/8 gap fitting. I then tightened down the hose clamp with a hex bit on my cordless driver. The clamp was tight enough to somewhat compress a groove into the rubber, and I tugged on the thing as hard as I could. It isn't coming off IMHO. I'm at work, but can send a picture later if you need.

I understand you are worried somewhat about the quality of the connection. You could get a 1/2 to 5/8 adapter like this:

But that would entail 3 hose clamps and a section of 5/8 ID hose to connect between the adapter and air gap. That seems like more points of failure. At any rate, I think you already have what you need to get this working.

It looks like mold or black mildew.

It commonly starts growing on and in the door gasket, which is somewhat porous. It collects on the filters until, as you have learned, you clean them. Then small pieces escape and stick everywhere.

Bob Villa and others recommend bleach or vinegar for controlling mold in a dishwasher. But your infestation looks too far advanced for such mild treatment.

You should use a cleaner called Affresh which was designed by front load washer manufacturers to remove mold and mildew build up.

Unfortunately Affresh and like products are not good at cleaning the mold from porous rubber parts. Try flexing the gasket away from the tub and scrubbing behind it with a stiff toothbrush.

If this doesn't work then you will probably have to replace the door gasket. The part costs around $80.