Method 1:
If you want to remove just the motor you need to unscrew the two screws holding it in place. Since there are three rubber hoses blocking your way you will have to remove those first. I would do that by first going in through the rear access panel and using plyers to squeeze and lower the metal clips holding the hoses in place, then pulling the rubber hoses down and off of the plastic tubes they're attached to. While you're back there detach the 4-wire connector leading to the motor you'll soon be replacing. Then carefully lay the dishwasher flat on the back and go in through the access panel on the bottom of the unit. The three black hoses will be attached to three plastic tubes on this end as well. Remove the hoses from these tubes the same way you did on the other side and lay them aside, keeping track of which one goes with which tube. Not sure it's that critical you match them up perfectly, but each has been playing its part effectively up until now so no good reason to change them up. At this point you'll have better access to the motor and should be able to unscrew the two screws holding it in place. You should be able to just pull the old motor out and either repair it or swap in a replacement for it. Note that when inserting the replacement there's a good chance it won't align properly (you'll see the shaft has a slit removed to allow it to turn the mechanism it attaches to). To resolve this apply pressure to the motor to push its shaft into the hole, while having a helper move the waterwall along its path until it causes the shaft and the mechanism to line up and the motor slip in. Tighten the screws, reattach the rubber tubes (from both ends), snap the connector for the new motor into place, and you should be done with the replacement. See below for a discussion on replacement VS repair of the motor:
Method 2:
This is slightly more involved and how I ended up doing it based on a Youtube video I watched, but not horrible. Basically, instead of removing the motor from the plastic assembly it is attached to this method removes the entire plastic assembly from the dishwasher first and then you would replace/service the motor. Why would you want to do all that extra work when Method 1 should be sufficient? Economics are one consideration. If you've decided you want to replace the motor rather than repair it then a new motor will run you ~$100, while a replacement motor, sensor, and the plastic assembly they both attach to won't cost you that much more money and it's all put together for you for a more complete repair. But let's just get into it...
For this method you start by going in through the rear access panel. You first remove the rubber hoses from the plastic tubes as you would in method 1 and then you unscrew the plastic fasteners from where the tubes extend up into the body of the dishwasher. This is easily done by twisting them part of a turn to get them to release, but the direction you turn them is the opposite you would expect to free them.
With the hoses detached from the tubes you'll now be able to reach the motor and note that the plastic assembly its connected to also has a plastic fastener ring, only much larger and on much tighter. This one should loosen counter-clockwise, unlike the smaller ones. You may be able to get it off by pushing a flathead screwdriver against the grooves around the edges or perhaps you have a fancy tool that lets you twist such objects. Once that is removed/free be sure to unsnap both the wiring connection to both the motor and the sensor.
Now go inside of the dishwasher, remove the trays, use a small flathead screwdriver to snap a pair of rubber covers off of the top of the plastic assembly with the waterwall jets in the rear of the unit. These can be tricky to see at first, but if you look closely you'll see them. Once they're snapped off unscrew the two screws underneath. In lifting up the piece you just unscrewed you'll noticed that it's attached to a metal guide that extends to the front of the dishwasher and at that point is only attached by a rubber snap that is easy to pull it away from.
With that assembly out of the way you'll still have a plastic tube extending up along the rear wall of the dishwasher, all the way to the top. This is held in place by small metal clips on the top and rear of the dishwasher that you can push to the side with a screwdriver, while pulling the plastic tube away from them, finally lifting it out of the unit.
With that piece removed the last remaining hunk of plastic in the rear of the dishwasher is the assembly the motor and sensor are attached to and will lift right out.
When reassembling you can mostly just reverse these steps, but I'd suggest saving the steps that involve reattaching stuff to the inside of the washing area of the dishwasher for last, securing the plastic assembly with the motor on it and locking it in place first. It's also important that the plastic fasteners are reattached snugly. The smaller three shouldn't need to be tightened more than by hand, but for the larger one that fits around the motor you're going to want to give that one a little more force, otherwise it will pop right off during dishwasher operation, you'll get an LC (leak) error, and you'll find yourself having to go in through the bottom access panel again to fix that. My suggestion for tightening the larger of the plastic fasteners is to attempt it through the bottom access panel (removing rubber hoses if necessary for leverage). Shine a flashlight at it and ensure that the plastic locks are turned far enough clockwise that it's going to stay in place and won't pop back off with minimal force.
Repair VS Replace Motor Considerations:
There's a Youtube video posted by Matt Rampone in which he walks you through the process of repairing the Waterwall Vane motor: It's a simple AC motor, but designed with a very weak piece of plastic in it that's likely to break over time, causing the motor to lose strength or fail completely. It's not clear whether this design flaw has been corrected so if you replace the motor it's not unreasonable to imagine the new one could fail again in another few years. If you don't mind tearing your dishwasher apart every few years and swapping out motors then simply swapping in a new motor is fine; however, Matt's repair suggestion should lead to a more durable, longer-lasting motor if you're not scared of attempting what he does. And if you screw up along the way, ruining your already-broken motor further it's not like you're out anything more than you would have had you just replaced it. I'm not going to go through his full repair procedure here, but in a nutshell, he disassembles the motor, uses epoxy to repair the weak piece of plastic, and also uses epoxy to permanently affix it to the permanent magnet inside of the motor, which should greatly reduce the chance of it failing in the future. The only real risk I can see to his method would be if it made the motor too strong, to the point where a future failed sensor/magnet in your dishwasher caused it to tear the belt when if it continued to drive it past its end-point. The other warning I'll give is that Matt follows what I've called Method 2 of removing the motor from the dishwasher, which does introduce the minor leak/error code LC risk I described earlier.
I personally tried to follow along with his example, somehow reversed the polarity of the motor due to not taking my time, tried to disassemble it again to resolve that, ended up stripping a screw hole in the plastic assembly it attaches to, and opted to replace the full assembly with motor and sensor (method 2 above) instead of attempting further repair on the motor.
Final thoughts:
What a poorly designed and documented feature by Samsung. The Waterwall concept sounds neat, but it's unfortunate that there are three separate components (that all would be expected to degrade over time) and any one of them failing make the bottom row and utensil racks of the dishwater largely useless. Then to further frustrate matters, if the sensor or magnet fail, both presumably would put more wear and tear on the motor (when it doesn't stop at the home position), causing it to fail sooner too. If you're having a problem with waterwall operation it might not be the worst idea to just replace all 3 pieces at the same time, while you're already working on it anyway.
the water wall, vane motor, logic board and wiring harness were all swapped out.
