The things to check. Tie rod ends, center link, idler arm, steering box mounting bolts and the steering coupler.

The coupler is usually evident by a "clunk" when you are turning the steering wheel.

Tie rod ends usually give you a "wander" or follow ruts in the rod as an indication of wear but extreme wear could give you the play.

The center link can definitely give you the slop feel and it could happen almost overnight.

The idler arm will usually give you more of a wandering than looseness but if the bushings completely fall apart it could give you the "play".

The steering gearbox bolts can snap and almost immediately give you the play. Check the bolts and mounting FIRST!!!!

Gearbox adjustment is always the LAST thing you try!