reverse gear box problem

[bnt5]

I have a manco go kart that has reverse on it and for some reason the reverse box clamshell is slightly apart causing grease to sling out. I have tried messing with it to get it back together but it is still gapped. I can push one side in a little but it wont stay and I am not sure why its doing this or what the fix is. The gap is about an 1/8". Any suggestions?

 

[Doc Sprocket]

Looks like an internal has gone out of alignment. Remove, disassemble, assess, relube, and reassemble.