I have an SPT brand countertop dishwasher. I forgot to push the red drain button before disconnecting the hose from the faucet adapter. The water pressure blew off this black rubber gasket. I can’t seem to figure out where it needs to go in order to make a nice tight seal again that won’t soak my kitchen when I turn on the water!
I figured it out. I’m not sure if this is the groove @ojait was referring to or not, but I was able to maneuver the rubber gasket into the spot inside the female side of the adapter below the ball bearings. I used a chopstick. The seal now is slightly leaky, exactly like it was until I messed things up yesterday. Thanks to all for taking a look!