I have a slight wobble just at the top of my headtube, Its only about 2-3mm laterally but its annoying! Ive checked that the fork isnt preventing the top cap compressing but i think it may be the top cap itself.
Mine is an M:Part cheap one, which just has one nut to expand it, ive been told that some top caps have two nuts, one to expand it in the steerer tube and one to compress everything. Is that true and if so could someone kindly point out a top cap which does have that function! I think that may solve the wobble as i cant get everything (spacers, headset etc.) quite compressed enough!