Not working lower spray arm has no water coming through upper arm is fine

With your dishwasher empty, roll out the bottom rack. The feed line for the upper spray arm runs from a pump outlet directly behind the lower spray arm spindle. This tube runs up the back wall of the dishwasher and mates with the upper rack when it is pushed in.

This feed tube simply snaps into place in the bottom of the machine. It is a high pressure line that makes an immediade 90-degree bend towards the rear of the unit. They have a tendency to pop out. When and if it does pop out you get almost no water coming out of the upper arm and you lose effective pressure in the lower arm, too. The cure is to push that feed tube back down firmly into the port until you hear it snap into place. While you have the lowere rack out it is a good idea to clean the intake screen out and check for any debris in the intake well.

If there is no blockage, your pump may need to be rebuilt or replaced. If your machine uses a solenoid valve to control weather the pump is washing or draining. The drain valve may be stuck somewhat open, diverting wash water down the drain. Or the wash valve may be not opening fully. Different machines work in different ways.

The little holes in the spary arms can block with general gunge etc. We use toothpicks, skewers to clear them. That sometimes helps.

There could be a couple of things that might be affecting the cleaning ability of your dishwasher.
First,there is a pipe/tube that runs up the back of the inside of your dishwasher. This provides water for the top spray arm. The spray arm has a feeder tube that covers the pipe in the back. If for some reason the feeder tube has come dislodged, the water just drips back down into the dishwasher, never touching your upper shelf. My children used to put large items into the lower shelf and in so doing, would dislodge the upper spray arm feeder tube. Just pull out the upper shelf and check to see that the tube is in the correct position. This should solve the problem.

If not, it could be that the upper or lower spray arms may have debris that keeps the water from being forced through the jets. You'll need to flush the arm with the spray attachment on your kitchen sink. I sometimes use tweezers or a toothpick to dislodge bits of peelings, paper, or bone that manage to get into the sprayer arm.
I hope one of these tips helps. If it does,please come back to fixya and rate my answer.

There is a pipe/tube that runs up the back of the inside of your dishwasher. This provides water for the top spray arm. The spray arm has a feeder tube that covers the pipe in the back. If for some reason the feeder tube has come dislodged, the water just drips back down into the dishwasher, never touching your upper shelf. My kids used to jam cutting boards and other large items into the lower shelf and in so doing, would dislodge the upper spray arm feeder tube. Just pull out the upper shelf and check to see that the tube is in the correct position. This should solve the problem.
If not, then the upper or lower spray arms may have debris that keeps the water from being forced through the jets. You'll need to flush the arm with the spray attachment on your kitchen sink. I sometimes use tweezers or a toothpick to dislodge bits of peelings, paper, or bone that manage to get into the sprayer arm.
I hope one of these tips helps. If it does,please come back to fixya and rate my answer.

There is a pipe/tube that runs up the back of the inside of your dishwasher. This provides water for the top spray arm. The spray arm has a feeder tube that covers the pipe in the back. If for some reason the feeder tube has come dislodged, the water just drips back down into the dishwasher, never touching your upper shelf. My kids used to jam cutting boards and other large items into the lower shelf and in so doing, would dislodge the upper spray arm feeder tube. Just pull out the upper shelf and check to see that the tube is in the correct position. This should solve the problem.
If not, then the spray arm may have debris in it that keeps the water from being forced through the jets. You'll need to flush the arm with the spray attachment on your kitchen sink. I sometimes use tweezers or a toothpick to dislodge bits of peelings, paper, or bone that manage to get into the sprayer arm.
I hope one of these tips helps. If it does,please come back to fixya and rate my answer.

Possible causes of spray arm inefficiency:
Loading large or tall items in the lower basket which stops the arm revolving.
Upper spray arm split along seam.
Upper spray arm blocked.
Under dosing of powder causing foam and reducing upper spray arm water pressure.
Blocked strainers reducing water to circulating pump, therefore reducing upper spray arm water pressure.
inefficient wash motor impellor (faulty)

you most likely have gunk inside the arm or holes not allowing the water to spray out and turn the arm. Otherwise, the arm bearing may be stuck and will need a gentle push to loosen up.

On the LG LDF xxxx dishwasher family, the Vario feature uses a motor/check valve to switch between "full power" cleaning from _either_ the lower or the upper spray arms, never at the same time. So, not seeing the upper arm spin during the lower arm spinning is standard operating procedure.

But back to your problem. Step one would be to remove the filter assembly again and make certain that there is nothing (debris, broken glass) blocking the white areas where the check valve rotates to switch between upper/lower spray arms. A blockage there ~could~ cause impotent spraying/cleaning.

If there is no blockage and the impeller remains in good shape, suspect a failing wash pump motor. Try to isolate the noise to that motor.

Watch for error codes on the display and report back what you find, OK?

Good Luck!

upper and lower connection should be same type of setup
missing part thus?
This sometimes is also caused by not driving in right the rack (closing properly) mating the connections tight. My old Bauknecht had this little problem.
Unfortunately I have no manual with parts drawings.
Still warranty?
Parts shop nearby?
Upper connection does have rubber ring or is a conical seal?
And when you fill the basket, no teaspones or such dropping too far down? My error many times.........