I'm trying to figure out why my Kitchenaid Dishwasher, model KUDP01LBS3, is so noisy. It's just out of 10 year warranty.

I tried to remove the retainer which holds the lower arm, and it won't unscrew. It just keeps turning. Is there something else I should be doing?

The basic problem is that the washer is extremely noisy once the water wash cycle comes on.

I've posted a http://www.youtube.com/watch?v=Sq8We9S9tXo video. Maybe somebody knows the sound and has an idea what's wrong?

Many thanks.

The YouTube video address didn't post in my question. Here it is again:

kitchenaid - YouTube (http://www.youtube.com/watch?v=Sq8We9S9tXo)

Here are photos of the reluctant retainer.

Most likely, something is in the arms. You will have to get the arm off to fix it. Here are the manuals: https://dl.dropbox.com/u/8010163/Kitchenaide%20Dishwashers.zip

Just to confirm before I start taking the dishwasher apart, did you hear the sound in the video?

The manual says

3. Rotate the rear feed cap (Fig. 3-11a) ¼ turn clockwise (Fig. 3-11b)
Fig. 3-11a Fig. 3-11b
4. The entire inner water tube assembly and the lower spray arm assembly can now be removed from the dishwasher tub.

Is that what I should do? Will I have access to and likely be able to clean out the arm if it's blocked or do I have to replace it?

Many thanks!

What video are you referring to? If the manual says to do something Make sure it's the same machine and then remove the arms. Check your filter, too. You can clean out the arm and it should be like new. This is just routine maintenance.