I removed the screw holding the spray arm to the bracket. I then put on the new bracket and tightened the screw. The bracket just clips on to the top basket of the washer. Easy as pie.

The part arrived the next day after order was placed. That is an amazing service.
When it arrived I noticed that the new part was re-designed but the dimensions appeared to be identical. Initially it was difficult to snap it in to position but with help of a screw driver it finally snapped in place. After re-installation of the upper wash arm all looked perfect. But the arm would not spin freely. It would bind against the bottom of the upper tray. Finally after about 20 minutes I noticed that the mount was slightly slanted to one side. This was not immediately apparent unless you look carefully. Further I noticed that the bottom of the upper tray was protruding lower on the right side. Finally I realized why the mount was slanted to one side. I removed the mount and turned it 180 deg.. Bingo all fits and works perfectly. I could have avoided the problems if an orientation directions were included with the mount. I suspect that a less technical individual would likely not figure it out.

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redesign of the Upper Spray Arm Mounting bracket no longer required it - the bracket simply clipped in -the diagram was out of date.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.

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.

Removed one screw which connects the upper spray arm mount, the spray arm feed tube, and the upper spray arm. Replaced with new parts ordered from partselect and it works as good as new. Highly endorse this website!

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.

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.

we removed the cracked pieces and attached the new spray arm. it took some time because the new arm looked different than the old,but we did it.... I was the one to order the parts needed i had never done this before my husband said it was broken and we needed to buy a new dishwasher ( he was less than thrilled about that) so i decided to do this myself and find the parts. my husband was very surprised that i did it.... AND SO WAS I... IF I CAN DO IT YOU CAN DO IT!

Installed the new upper spray arm mount. First I installed it backwards which made the blades not turn freely (rub against top rack basket). Turned it around and was good to go. I found it helpful to remove the top basket in order to do this. Note that this clip is gray while your dishwasher tines are white. This does not cause any harm.