Sublime Master john63 reveals the kata for this encounter:

<<<There is a grinding noise when first started up>>>

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Many Samsung DMR57 & DMR78 dishwashers are known for developing a rattling/grinding noise during DRAIN MODE.

This is usually caused by a broken plastic mounting tab from the upper rack ADJUSTERS.

Each side of the upper rack has a tan/gray square RACK ADJUSTER---after a mounting tab (or 2) breaks off---this piece of plastic eventually ends up in the DRAIN PUMP HOUSING.

The DRAIN MOTOR should be removed to inspect for debris.

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<<<after a minute or two I get 9e error code>>>

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A normal amount of water in a DMR78 dishwasher would be---at about 1 inch past the HEATER SHIELD in the tub.

If you've tested the SWITCHES on the LOW LEVEL SENSOR---then they're not at fault.

Press the following buttons at the *same* time:

DELAY START--NORMAL--POWER(button)

The word "ALL" appears for 3 seconds followed by "t1"

(NOTE: Test #1 checks the functions of the INLET VALVE--FLOW METER--LOW LEVEL SENSOR)

Press the DELAY START button---the DRAIN MOTOR will run for 45 seconds. Then---water will enter the tub.

When the PULSE COUNT (on the display) reaches "660" or greater---press the NORMAL button four times.

A flashing "t5" will be displayed & water will drain for 30 seconds. After 30 seconds---the "t5" will stop flashing.

Press the NORMAL button again---"t6" will be displayed. The word "OFF" should appear in the control panel display---indicating that the LOW LEVEL SENSOR SWITCH is in the correct position for *No Water* in tub.

If the INLET VALVE--LOW LEVEL SENSOR--FLOW METER function normally----replace the MAIN BOARD.

Source: Samsung dmr78ahs dishwasher grinding noise and error code 9e