Jackson-
That machine is in perfect condition. It looks brand new inside.
The balance ring is filled with water, seawater, I believe. It's why these machines have such amazing ability to complete cycles with the most out of balance loads...even washing a single pillow is no problem for it. In six years, I've never had mine shut down because of an out of balance condition...it always completes the cycle.
It's very hard to say whether or not the struts are the issue. Mine do not leak oil, I know that from working on it. You may have a bad one. But with the panels off the machine, if you re-assemble the tub and top, you can start the machine up and see how it reacts during spin and see if you can hear where the noise is coming from while watching for excessive tub movement. It should spin pretty steadily, just some minor rocking, but definitely no twisting of the tub. You'll get some "tub twist" when the machine shuts down after the final high speed spin with a load in it...that's normal.
When you re-assemble the top, make sure all the rubber flanges are correctly in place under the top lid of the machine. Their placement is obvious, but if they are outta place, the machine will splash water over the tub while it's washing, causing unsightly rust underneath.
I hope you can return the u-joint and leveler???
Another thing I would do