front diff slipping and making a clicking sound, help please

[Danny Harrison]

I got a caster s10b for our lasses kid to start racing with. It was fine but 1 of the wheels binded while on the track and now it sounds like the front diff is slipping and making a clicking sound under acceleration and braking.

I've stripped it down and checked the gears and they are fine. I took the diff apart and put back together tightening to what felt right too.

I cant figure it out, I'm 99% sure its diff related. If I hold the car against the floor and turn the spur gradually by hand, I can feel the tension building then its released with a click sound.

Any ideas what it is? Should I just buy a new diff assembly?

Thanks in advance for any advice recieved, I'm still reletively new to this game