I have not googled this or checked instructables so any solution others have I have at this writing moment not seen.
This is my story
When opening the cheap toy I see the problem. A gear is stuck between two other gears, probably this has been manufacture because when I look at one gear that is to large so to fit the other gear holder should have been smaller. Instead they broke it. The part that was missing was not inside the toy.
First I thought I would just glue the gear pin in place. Fail.
I needed some support for the pin.
A wooden plug.
2 x Drills and a drilling machine.
Superglue (I used two component glue, my feeling is that it got a better substance)
End result = Perfect fit.
Step 1: Clean the Area
Step 2: Wooden Plug
Use a bigger drill, that's the same size as the original
gear holder and drill in the smaller hole.
Cut the plug so its the same hight as the original gear pin
Step 3: Some Vaseline, Glue, Toothpick and a Hole
Step 4: When Glue Is Dry
Use your sharp knife and cut off the glue that has run over.
If your plug is to high fix it =)
Fixing the new pin holder size.