Sessions waiting on Broadcast mesg queue transition.

After After adding and deleting an event queue subscriber,
there are now 3 database sessions waiting on BroadCast mesg queue transition

MetaLink note ID 465498 was implemented to monitor jobs exceeding the set maximun_run_duration.
The steps were implemented as described in Note ID 465498,
then they were backedout using the following procedure:
1) Deleted 'REPORTS.SECOND_JOB'
2) Deleted 'REPORTS.FIRST_JOB'
3) dbms_scheduler.remove_event_queue_subscriber('myagent');
4) dropped table REPORTS.JOB_OUTPUT

I then noticed three database sessions [716(E006), 701(E007), 1036(E005)] waiting on Broadcast mesg queue transition.

How do I get rid of the waits?
and is there a way to check to be sure there is not a queue building up in the database?