I looked on the internet for similar descriptions for similar models and found many angry reports. Most said that the rotor assembly was bad as the nut that held the rotor and other parts together had loosened and allowed slippage between steel and plastic splines. Yes, I know that sounds like trouble, but apparently not to LG when they designed it. Most buyers complained that the part was covered by warrantee but not the labor and labor had been quoted as $400 to $600 dollars. Time to buy new competitor washer. I removed the back of the washer, 1 minute with screwdriver, 4 screws on mine. I saw the loose nut that everyone spoke of and removed it with adjustable wrench. 1 minute. At this point the rotor assembly was removed with some even pulling and jiggling. In the middle of the rotator assembly was what was left of the ground up plastic/nylon splines. Easy to see what stopped the machine. I decided to assume, yes I know, that LG would require conformation of damage by a "proper" technician before paying for the damaged part. This meant a minimum of $90-$110 in my area just to show up and look at what I had already done, therefore to hold my costs down, I simply decided to order the apart for the best price and shipping time I could find. I paid approximately $55 for part and shipping on a Sunday night, internet. I expected, hoped, to receive part on Wednesday even though not promised by parts company. Part arrived middle of the day on Wednesday. I installed the rotor assembly by lining it up and sliding it on the shaft. I added a drop or two of Loctite on the shaft threads and replaced the nut and tightened it up. 5 minutes. Hooked up the water and electricity and started the machine. Worked totally normal. Replaced the back panel. 1 minute. Shoved machine back in place next to the dryer. 1 minute. Have been using for three days and machine working normal just like it had before damage. This appeared to me to be the least expensive way to get up and going again even though LG got off scottfree for their poor engineering. My LG Model Washer: WM0642HW
About as easy as it can get. Have had washers that were harder to remove back panel than completely repair this one for this particular damage. Take the back panel of washer off and you will see a 12" - 14" diameter circle of the rotor assembly. This piece does not just fall off after removing holding nut as rotor is covered with magnets on its inside that tries to hold it onto the shaft. Just wiggle and pull and it will slide off.
DC 9/19/15