XRAY - Model racing cars

My car suddenly started clicking when accellerating when I ran it today. When I hold the spur gear and the left back wheel, I can enforce the clicks by forcing the right back wheel around (not using excessive force). When I opened the back diff, I found no error. Xray, what do I do? I have the metal gears.

Update: It's been a few days without an answer. Is this a support forum? Do anybody know a better place to get help than on this forum?

check all the gears carefully, I find that an occasional nhard landing with the slipper to tight with damage one or two teeth on the gear, check very carefully, also check you bearings aswell

I've heard my XB4 click also. I have been going mad because I can't find it. Anot her XB4 owner had the same problem. Does everyone recommend a fix? I notice it on a landing when I hit the brake.

Check your play between the gears. How big is it? Hold your center drive and turn the diff. You should feel the play and it should be about half a mm. The metal gears still benefit from being shimmed properly. I added a 962100 shim to either diff on my kit on the gear side to get the mesh closer.
Also check your bearings and your drive pins.