How are you adjusting reinforcement to reduce maladaptive behavior? Can you reinforce a more appropriate, alternative behavior to replace the maladaptive behavior?
When possible, adjust the sequence of tasks so that a particularly difficult task (e.g. entering new inventory into the system) is followed by a break initially. Can you adjust the sequence by getting permission from the supervisor to grant an additional water break after certain tasks, at least initially in training? Work with the student to identify appropriate break activities that will be motivating to him.
If certain necessary work tasks create agitation or frustration, consider breaking them up into shorter segments. Consider putting a self-calming routine on the schedule prior to the difficult task. Reinforce the student for using the self-calming routine and for completing the difficult task with additional reinforcement after work, if possible.
Are you using labeling and social praise to make the contingency between desired behavior and reinforcing consequence clear to the student?
In some cases, the student will try to seek out too much confirmation from supervisors and co-workers which may create tension on the site. Consider scheduling predictable, specific times when someone will give feedback on performance. Over time, the goal would be to fade out the frequency of that feedback to a rate that aligns with what naturally occurs in a work site.
What reinforcing consequences can you arrange that are more naturally or intrinsically connected to this targeted behavior?