Brand new LG LDF6920 makes a whistling/high pitch squealing noise even during 1st test run, no dishes no contaminants added. It is during the wash motor cycle once the wash pump gets up to speed *screech*. I am sending back unit. should I try another LG and hope for better luck or move to another brand?

SOURCE: ldf6920 whistles and chirps the water valve adjustment doesnt fix

Hi,

This can be 1 or 3 things.
In theis machine your inlet valve is protected by a filter. When the inlet filter is clogged by limescale it will whistle like crazy.
That is one
2 the inlet valve can be defective ( number M210) in the sites I will provide.
3 the seal of the airbraker can be leaking.

HERE is service manual of the LDF6810 which is actually more or less the same machine.

HERE you can see similar drawing +parts list so you can order

Good luck

SOURCE: high oitch noise during wash

As motor bearings wear out, they can become quite loud when the motor runs. They wear out quickly if they frequently get wet, because the water washes away the motor bearing grease. Bearings can get wet if the spin seal is defective. Then there will also be water leaking onto the floor beneath the dishwasher. Replace the seal if it leaks (read about the main tub seal in the "It leaks" section, later).If, from beneath the dishwasher, you can see a round, plastic disc that's mounted to the top of the motor (a "slinger"), it may have broken free of the motor shaft. If so, it could be rattling around the shaft while the motor is running. If that's the problem, you need to replace the motor.
If the heater fan bearings are rusted or worn, they may squeal, or scrape loudly during the drying cycle. If this is the problem, replace the fan motor. Alternatively, the fan blade may be loose. If so, you need to replace it.