If the oscillation crank handle comes off, and the crank goes inside (retracts), you need to push it back out to reattach the crank handle. Figure 1 shows what it looks like when the crank has been pushed inside. As you can see it is flush with the side of the ball machine.
In Figure2 we see the end of the oscillation crank. (RED ARROW) It is a threaded metal rod. In order to push it out, remove the feed tray by unscrewing two phillips screws at the center of feed tray.
Figure 3 below shows you the same view in Figure 2, but with the feed tray removed. Push the oscillation crank rod in the direction of the black arrow, towards the outside of the ball machine.
Once the crank is pushed out, the end will be visible on the side of the ball machine. It will appear as a round “nub” with a flat side. See Figure 4. The black crank handle can now be put back on.