Gear Collision detected, how to avoid

Hello All,

I am setting up this gear differential for a class using bevel gears.  I can get it to run properly, however if you look at this picture the gear on the right side and the bottom gear are colliding.  How do I overcome this.  This is a manufacture model and I have been using the helix and pressure angles listed by the manufacturer as well as the pitch listed.  Any help would be greatly appreciated.  Thanks.