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Replacement parts for General Electric HDA999M-20 | AppliancePartsPros.com

Most common problem is that the unit is not getting enough water.
On most units it should fill to just below the heating element.
One way to check is visually or open the door after each fill and add a couple quarts of hot water, if it now runs OK then low water level is the most likely culprit.
There is a filter screen on the inlet side of the water valve, it may be partially clogged with crud. Remove the valve and clean the screen. Do not remove it as it is there to keep crud out of the valve which could hold the valve open and cause a flood.

Check that the spray holes in the washer arm are not plugged.
Also check that it spins freely.

Remove the sump cover from inside the tub (center on it's floor) and check inside the sump for debris. Be careful as often there is broken glass in here. Also check that nothing is wrapped around the chopper. Take note how the inside piece goes in, put it back in the wrong way and the chopper will eat it.

Just FYI is that in spite of all the marketing granular detergent is still the best.