Fixing?
I'm afraid you can as well forget about it and just buy a different different-ial
The diff you got is a Comet SCD1
and it's out of production, there are still axle shafts seals and grease available.
gears /cases are NOT
a case can be rewelded by a professional welder...
a missing or shot gear however is going to be tough.. maybe you find a generic replacement (linngear or so? but I never seen someone doing or even mentioning such replacement)
Look out for a Peerless 100 with a 1" axle instead it's a direct replacement really
it's of different shape (more like a soda can) and you will also need a new sprocket
'sid
PS check out mfgsupply.com for example or staton-inc.com
[
EDIT]
Oh forgot.. that is a Carter Brothers kart..
superwheels decal gives it away.. I'm inclined to call it a 1765
[
EDIT II]
Ohhhh look what I found:
https://shop.stollerlawnandgarden.n...ifferential-kit-detail.htm?productid=-1001973
a comet scd-1