Yes, That's the place it goes. When new the edges of the hole was staked in several places to hold the ball in. After a few years of use the push rod wears the stakes away. This lets the ball fall out. If you clean around the hole you might see the stakes.
It will fall out again. The best way to keep it in is to use a dab of grease on the ball and in the hole it goes in.
While you have the cover off I might suggest removing the inner part of the worm mechanism from the outer and clean them well, inspect the plastic hal of the worm for damage, they do crack betwen the threads. Relube well with your favorite grease.
The worm and cable need to be properly lubed often for easiest lever pull.
Leo
