The only X steering issues I have had were that the fan shaped sector gear was strangely worn in the center. The small gear on the steering shaft showed very little wear. It was like it was a tempering problem. It is a tough area to see, but inspect the gears and bushings for wear.

The X5xx Select Series has butter smooth steering and no chronic problems that I have heard of.

Jack the front axle off the ground.

Manipulate the front wheels by hand slowly from left to right and back.

See if you can feel any binding in the axle spindle (11 or 16) where it goes vertically through the cast iron axle (6).

See if you can feel any binding in the (tie rod) steering link ( 17 or 30) moveable joints.

You can easily see the steering sector gear and shaft (18 & 29) from under the X500. Look carefully and inspect for broken tooth or teeth.