Lower arm won't spin

Remove the upper wash arm from the rack. Examine thoroughly. Look for hair line cracks especially if the wash arm is plastic. Top rack wash arms have spray holes on the top AND bottom. Check both places. Sometimes small fish bones will clog the hallway of wash arm not just the holes. After years of use, the wash arm will bow especially plastic ones. Be sure the water connection to wash arm is Secure. If you think the wash arm is not spinning, try this. Place a old cell phone inside a sealed glass jar and start recording video from the lower rack. Be sure jar is Secure. The light from phone will come on. You might see the problem this way.

Make sure the center loading is not obstructing the water jet to the top shelf. Top shelf is only for glasses and saucers , use Jet-Dry .Pre rinse and clean bottom pan strainer from dirt debris.

Make sure that that upper arm is free to turn. Check it while you have dished installed, because sometimes, dishes on the lower rack may stick up too high and hit it. Otherwise, check the back of the water-supply tube attached to that upper rack.... Is it lining up with the water feed port or hole at the backof the dishwasher? Is there a gasket that is either ripped or missing? And check that wash arm carefully.... Might it be split or bent? Are the holes on the bottom clear? (Those holes are usually angled to push the arm around; if they are clogged, the arm won't rotate.)

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Hello, check the sprayer arm on the top of the dishwasher inside and to see if it spins. Don't block this spray arm with glasses or dishes that could block the operation of this sprayer cleaning arm.

Now, if it not spinning, check out the fitting arount hing bolt. If this wore out then you will have water pressure lose. Replace if need be. Also, check the feeder water spout that runs the upper spray army, it could be pluged. GB...stewbsion

With the LG LDF6810 model, this is not a common problem. Please try the following test, With and empty dishwasher, add a small to normal amount of dry dishwasher powder and run an (empty) load.
Check to see if any soap remains in the dispenser cup.
If any remains, here are three things to do: 1.) Upgrade your dishwasher detergent to a name brand powder (e.g.: Electrosol or Cascade)
2.) When you load the dishwasher, do not place large items in the front, near the door/soap dispenser.
3.) Before you load the dirty dishes for the next several loads, with your hand, turn both the upper and lower wash arms so they point at the door. Load as you normally do and push the racks fully in. Before you close the door, spin both the upper and lower arms and confirm that they spin freely and neither hits anything. if either does not spin freely, pull out the rack and arrange so the arms can spin freely.
I find that the only time I have left over detergent powder is when the wash arms do not spin freely.
This is a common problem on most every energy star/water conserving dishwashers.
Please report back what you find, OK?

ok so If your dishwasher has worked fine in the past but, suddenly, your dishes aren't clean after the dishwasher completes all cycles:
1) Check your water heater's temperature dial to be sure it hasn't been changed recently.
2) Be sure dishes haven't prevented the detergent dispenser from opening properly during the wash cycles or kept the spray arms from turning, the lower arm from rising, or the spray from reaching the upper rack's dishes.
3) During the wash cycle, listen to the spray arm spinning inside. If it seems to be spinning poorly, clean out the spray holes in the spray arm(s) with a stiff piece of wire; wait for the machine to cool, and then remove the spray arm(s) by unscrewing the hub cap and lifting the arm(s) off Regards Gizokieth

Check the upper arm for free spinning, then remove the arm and check that the seam between the upper and lower halves has not split somewhere. Also check all the small holes for debris plugging. Run the machine in wash cycle for a little while with the upper arm off--that should flush out anything blocking the pipe up to the arm. If still nothing from the upper arm, tear down the lower arm assembly down to the deck while noting position of all parts removed. Clean the big screen at the bottom in white vinegar and hot water. Inspect the holes in the bottom for anything blocking them.

Had similar problem with our Maytag dishwasher--we removed all spray and screen components to the inner case, cleaned the intake screen below the lower spray arm, repaired a split upper spray arm, and inspected everything for cracks or other distortion. All of this helped some, but finally improved things by changing from liquid detergent to a "packet" type. Our water is somewhat hard and builds deposits on the screen at the bottom. Run a no-dish cycle with a cup of white vinegar in the bottom.

Almost all of the problems mentioned above will be solved by having the owner buy a name brand detergent powder (like Electrosol or Cascade) and using a little less than you think you should.
For those who continue to have problems with poor cleaning, you need to remove the lower spray arm (pull straight up firmly, then out) and then remove the 9 screws that hold the filter in. Using a flashlight, inspect everywhere in the sump area (be careful of broken glass!) Remove all debris and especially look for something blocking the white check valve that is driven by the Vario motor to control the alternation between the upper sprayer arms and the lower arm. Reasemble and test.
If inside dishwasher is a mess with white mineral deposits, recommend you place a bowl filled with white vinegar on the rack of your empty DW. Start a quick cycle with no detergent added.
Check out how clean it is when you are done!
If you have problems after this, please post back what you are seeing.
Good Luck!

id try removing hte lower filter plate . 5 torx 15 screws will gain oyou acess to lower sump and 2 more torx screws that will acess you the chopper assy, prhaps filled with debris not allowing good water flow,