Battery operated clock, pendulum won't swing

The clock works, the arm that holds the pendulum works (swings back and forth just fine). However, as soon as you mount the actual pendulum on the arm, it will swing to a slow stop. This is the second battery operated clock I have had this problem with.

Is there some trick to fix this or do I need to replace battery movement?

And, what is causing this to occur? Cheap movement, someone moved with pendulum attached, something fell off?

Thanks You-
Cassandra