I noticed the upper bushing washer was worn thin. this caused the lower spray arm to rise too high and wobble during all the wash cycles. Also the rotation of the lower spray arm was wearing grooves in the lower bushing.

I removed the retaining nut and simply replaced teh defective parts. While I was at it I figured equal wear might be evident on the upper spray arm so I bought a complete rebuild kit to bring all rotational parts back to new and equal preformance that was achieved by removing the ss screw and removing the upper spray arm, bushing and clip then replacing them in the order of removal. Noticed a huge difference in the quality of the washed dishes!! Thanks Parts Select 100% to yoru company!!

The part came so fast without extra shipping. It took only 10 minutes to replace water tube and upper spray arm. I only had to remove one screw. Replaced with new parts and reinstalled screw. It was easier and cheaper than calling a repairman.

This gets a little lengthy... but it explains where Cascade Dishwashing Powder came up with its brand name - it's been a cascade project.
I started by replacing the Middle Wash Arm Tube as the old tube developed leaks. As others have stated this is a new design but directly replaceable and easy to do.
This didn't solve the cleaning issue so reading the experiences of others on this site realized I also had broken parts in the Upper Spray Arm Assembly and the Upper Wash assembly. I replaced these and the dishes were suddenly much, much cleaner. These were very easily replaced.
I did find that I did not need the Mount for the upper spray arm (PS402277) as a redesign of the Upper Spray Arm Mounting bracket no longer required it - the bracket simply clipped in -the diagram was out of date.
Everything seemed to go well for about 3 loads when the dishwasher started leaking heavily out of the bottom of the door. I then noticed that the lower Wash Arm Bearing Ring and the Seal, Lower Spray Arm had disintegrated so I replaced those but this didn't affect the leaking. Someone had stated that if the lower wash arm assembly had too much 'wobble' that it cause 'waves' that would leak out the front door... mine had some wobble so I added a nylon washer from Ace Hardware that reduced wobble but still leaked.
I then replaced the Door Seal Kit - this was by far the most difficult part as the door needed to be removed and it was somewhat difficult - and it seemed apparent after we had removed the door that these parts weren't the problem but we replaced them anyway.
Also, someone else had noted that they had to attach the door seal (this is NOT the gasket that goes around the door opening) with a sealant - I had the same problem; the original seal fit tightly with friction but the new replacement required an adhesive - I used silicone. Still leaked.
From here on I can't guaratee any useful information: I took the strainer screen out of the bottom of the dishwasher and found one slightly loose screw holding what I believe is the 'pump outlet' according to the diagram. I had also read that the water fill is controlled not by the float at the bottom of the washer but by the electronics and it was suggested that I disconnect the DW from the power to 'reset' the timer, this I did and hit the 'Cancel' cycle a couple of times to make sure that all programs were cancelled. Whether any of this made a difference I have no idea - except that the dishwasher suddenly stopped leaking and hasn't leaked a drop for at least 20 washes. So I don't know, for sure, why it leaked or how I fixed it, but it's working and washing great now - except the tines on the lower rack are beginning to rust out and breaking off. The rack is pretty expensive but so far I've saved a lot of money and my family thinks I'm a dishwasher genius.

As others have described, this replacement was very easy. The new spray arm is solid plastic instead of rubber (which had deteriorated and was the part that needed replacing). So it should last longer.

You have to keep and reuse the mounting bracket that attaches the spray arm to the upper rack, so don't throw that away!

The replacement was super-easy, and as others have commented, the dishes haven't been this clean for a long time. Well worth it.

The mounting bracket was broken.

The parts ordered were a direct match due to the fantastic pictures supplied on this site.
A dealer wanted to order it and then I would have had to drive and pick it up - no way.

partselect.com first time user - very easy.

The video offered was perfect and walked me through the exact process and gave me the confidence i could handle this repair myself. It was very intuitive and went step by step. Thank you for taking the time to post the repair steps on video. Ordering the parts was very simple and they arrived on time. Flawless in every aspect. i would recommend your company.

First of all, we were very impressed with the ease of finding the parts, the ordering, and the velocity in which the parts were shipped. We received them the next day. I had to remove one of the screws from the old kit, since the new one only came with one. I looked at the diagram on the website of the assembly, and also remembered what the assembly looked like before I took it apart. The first time I tried it, I could not get the spray arm to spin without hitting the dishwasher rack. Since I had ran out of time, I had to wait until the next day. Once I started, I realized that I had the mounting bracket on backwards. Once I turned it around, I tightened the screws, and it was done within 5 minutes.

We were told by a repair guy to buy a new dishwasher-about a $900+ cost to replace. Then a local parts place and Sears each quoted us $85 for the part plus $129 to come out. Found your website and bought the part for $17. Also bought a hard rubber gasket that fits on the bottom of the door for $8. The brackets that came with that last part were the hardest to install, but the gaskets took 15 minutes. We did glue another strip of the long door gasket along the area under the door lip. Works great! Saved over $800. You rock!

Removed upper basket and installed the arm. New snap in didn't require phillips screwdriver as old one and new support had split to insert. Replacing upper spray spinner dropped screw down around pump. This caused misery unassembling lower covers to receive Stainless
Steel, so magnet won't help ended up with mirror and hemistat to reach through large screen figures. So make sure to put towel or something in the bottom to catch parts.

Bottom wash arm bearing and seal were severely worn and leaking. Replaced in about one minute with new parts from PartSelect.com, and took the opportunity to clean out the arm -- stringy, fibrous matter was clogging two jets.

Top arm horizontal rubber supply tube was disintegrating and leaked. Replace with Spray Arm Kit -- this took maybe two minutes!

Lastly, two to of the upper right-rear folding rack tine clips were broken -- replacement was difficult as the old, broken clips were very stiff and came off only after much physical persuasion! New clips were installed easitly -- in a "snap". Time ~ 5 minutes.

Best of all, the new parts were delivered to my home within 36 hours of my internet order. I thought the prices were fair, too. Thanks.