2. The bolt at the top of the housing holds the bearing inside tight.
3. Loosen the bolt (hold the nut with a spanner if yours has a nut on the other end)
4. Housing with retainer bolt removed
5. Remove at least the bottom bolt from the housing (if you've removed yours from a kart completely you shouldn't have to do this part - you'll have already removed them in the process of removing it from your kart)
6. Orient the bearing with the recess in the housing facing upward (you'll only see the thin recess on one side of the bearing about half way up on the side between the bearing and the housing). Push the bearing downwards at the bottom hole of the housing, ensuring it rotates evenly and pivots half way up the housing on both sides. Sometimes this requires more force if the bearing has been in for a long time or has been wet and gummed up - if that happens, place the housing on a flat surface and push the bottom of the housing down toward the flat surface until the bearing starts to rotate inside.
7. Keep rotating the bearing evenly.
8. Rotate the bearing until it moves 90 degrees and the little nodule or bump is lined up in the recess in the housing.
9. In this picture you can clearly see the recess and the nodule lining up.
10. When the bearing is oriented this way, the housing will just drop away. If it's gummy or tight, push the housing down toward the flat surface lightly and it will separate from the bearing.
11. Remove the bearing from the housing.
12. Installation of the new bearing is exactly the same process in reverse. If you find it difficult to installl the bearing, a trick is to push a flat-head screwdriver into the joint at the top of the housing to allow it to open up a little - WARNING don't open it up too much or it will crack and break.