You probably have too many miles on it..just won't register anymore....
You should have asked this question in the LS 400 board. Anyway hopefully your cluster have the same common problem with others. You need to replace all the surface mount aluminum capacitors on the cluster's PCB boards. I suggest you read the Pinned / Sticky topic post on most LS 400 forums.
You need to remove the 2 screws that hold white LCD plastic holder. Remove all solder at bulbs joint. Slightly bent the LCD to expose the bulbs under the plastic holder. Install new bulbs. Solder the joint. Put everthing back and you are done. You can contact me if you are still have questions.
I don't think the seat move backward on my 94 LS400. However, the seat does move backward on my Infiniti Q45. Perhap you were thinking of that particular model?!
By the way, are you really located in VN?