Hi I am a new member and read your post.
I have had a LS430 for 5 years now 2001 plate and have had the exact same problem. I had it taken to dealer to fix and as expected was very expensive £1,600 for a new steering lock column.I have just picked it back up this weekend and is as good as new.The only alternative the dealer gave me was a bodge up job, change the car or fix it properly which is what I chose although expensive.They said that this has never happened anywhere before so I was supprised to read your post.