I don't know what you have or have not replaced, but this is a common issue with steering. The lower bearing/s get hammered (especially the LHS) if n when the pre-load isn't correct, causing the bearing cone to be damaged like this

the one shown has scuff marks, if those marks/indentations get to just a few thou deep it will cause problems with steering not returning, also you would need to check the bearing as well, this is the bearing

I did have a cup n cone that had some horrendous damage, when they were together in your hand you could feel the Klunk Klunk as the rollers went from one indentation to the next, but I cannot find it to show you all, anyway if that's not your problem it might be a future reference for somebody else, cheers Dennis