I removed the top and found that all four washer suspension straps (#22 in the diagram below) were missing. I think that a new suspension strap will connect to the inside wire of the washer suspension rod (#23, below).
However, there's no bolt hole for the suspension strap to attach to the basket. It looks like they connected the suspension strap to the basket with Zip Ties. How do I connect the suspension strap to the basket?
Also, what are common causes of all 4 suspension straps breaking?
thomasortega referenced the motor counterweight: "Also check if the motor counterweight is on it's place.... if it falls, the motor weigh causes an unbalance."
How do I check the motor and the drum counterweight?
The counterweight is a metal block attached to the tub, opposite to the motor.
But as mentioned above, the straps are missing (probably broken, so you'll find a piece of them right down the suspension arm and another piece hanging on the top of the tub) Missing straps is the very first cause of OOB.