I fixed my 4WAS system for $5 recently. 2011 M56 with 120K on it. The system is basically 3 parts, the bar or strut that attaches to the cross member and the wheels on each side, the actuator assembly which is the other two parts. I'm pretty savvy when it comes to this type of stuff from working with heave duty equipment and intervals of other stuff. So I was bewildered as to how this little motor with a bar would cost some much freaking money! There are older cars with the HICCAS system but Infiniti decided to run ALL of the safety driving features through this system, well not through it but by it. So one day if figured well it doesn't work anyway so I may as well get under here and jack around with it. So looking under the car, you'll see a metal gear housing attached to a black round actuator. The gear housing has grease that somehow, over time, matriculates over to the actuator that is basically a set of windings or electrical coils.
Philips screw driver, towel, toothbrush (or some type of small, soft brush), brake cleaner
1-put car on stands
3-get under car and remove the two Philip screws on the black actuator (ONLY) not the 10mm or 12mm bolts on the silver metal housing.
4-remove black housing. Remember the housing is magnetic so it may be a little tough to pull off. If you see grease, remove it with the towel, and clean it with the brake cleaner. I spayed the brake cleaner a total of 3 different times after waiting 5 mins to let it dry.
6-send me the $4,500.00 that you saved for my sharing LOL
OH and since you've read this far, here is a crappy YouTube video of me explaining it.