HPI MT2 DIFF
 

I took apart both my diffs to install new heavy duty gears the rear box went together fine but the second is binding and locking up. The problem isn't with the new gears it seems to be coming from the bevel gears in the diff case part(a431a) it happens when i try and spin one diff shaft the other side lockes up i.e. spinning one tire to get the other side to rotate in the opposite direction.

[link=http://www2.towerhobbies.com/cgi-bin/wti0095p?FVSEARCH=a431&FVPROFIL=++]Diff Case[/link]

These are the gears in question [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXBTA4&P=7]Bevel gears[/link]

These gears were perfectly fine before i took it apart and there's no sign of wear or stripping. I took it apart and reassembled 3 times making sure everything was in place and i just cant figure it out. If anyone has any ideas let me know thanks...