Could be several things none of which mean panicand buy millions of headsets. 1. not enough headsetspacers, you should have 5mm of space between the top of the forks and the top of the stem, without this the forks wobble as you described. Very easy to solver add more spacers. 2. you may have crushed your star bolt presuming your using one, if you have over tightened yourtop cap your star bolt will be bent and wont hold the headset. This also resultsin the wobbling youdescribed, just buy a new star bolt, or better soloution an azonic headlock or something similar. 3. Well its a king so it shouldnt but the bearings may have some movement inside the cups this= bad and money but doubt its that with a king. other things it could be badly mounted crown race (even if it looks ok) Part of the headset missing. (bit useless i know) destroyed headset. Flared headtube. Hope some of this helps, as i had the same issue, mine was both of the things i stated.