Shove lube down the post shaft before installing handlebars
Unfortunately ive had some bad luck with my forward mount posts. The first was a CR post very similar to Wildchilds. The ball joint on the bottom came loose. So I got a Wildchild post and after 2 rides the same thing happened. He was awesome enough to replace it but sure enough after another season my 3rd post is loose again.
After all this happened someone mentioned that I should have shoved a heap of grease/lube/oil down the shaft so that it could lubricate the ball joint at the bottom. I am unsure if that helps or not but it cant hurt!