Q: I'm having trouble replacing the cv axle. Do I need to replace the rings around the spline that goes into the transmission?

The rings you are pointing to in the video are actually the retaining rings. Unless they are broken, they really shouldn’t need to be replaced. The ring on the male part of the splined shaft should pop into a groove in the female part of the socket, on the inside. These types of splined shafts with a retainer are normally installed with a blow from a soft faced hammer. It is normal procedure to put the shaft into place, while lining up the splines, and then giving the shaft a swift shot with the soft faced hammer. You will need to gently pull, or pry, on the shaft to be sure it is correctly seated, and doesn’t pull back out too easily. Also, it may be necessary to try to pop it in like described, and if it doesn’t engage, you may need to pull the shaft back a little, turn the shaft a bit, and try the installation procedure again. If you need help completing the installation, contact a certified mechanic, like the mobile mechanics at YourMechanic.com.