Mirage Drive Sprocket Shaft - for both newer and older drives.
The sprocket shaft is held into the spine by a set screw located between the sprockets. Since it is stainless steel, it should be a low failure item. But it is possible to bend the shaft if the kayak is dropped when the drive is installed.
On the newer drives, the sprocket installs directly on the shaft. For older drives, there is a bushing between the shaft and sprocket for lubrication.