Just an update in case anybody else has this issue and wants help. Here is what I have found from my searches/experiments. There are multiple issues:

1. 95% of the time the UL code can be fixed by buying the suspension rods. They were like $60 and I swear mine were fine because they were just springs but I spent the money and replaced them and magically the UL code went away.

2. When I looked under the washer I could see where something brown (rust, grease, etc.) had spun in a circle under the washer. More googling revealed that my bearings were bad. Apparently if they go bad it is possible to make the stabilizer rods go bad. But the bearing kit is like $60 and you have to buy a tool to install them for $60 so I can't afford to change them right now.

3. I did notice that my UL code still happens when I have an empty basket. I think this is caused by soap building up beneath the tub and causing it go to unlevel.

My plan is to take the basket out tomorrow and remove the soap buildup (assuming it's there). Then on payday I will do the bearings. I'll post the results in case it helps others.