Discussions regarding the preparedness of Y-end for pump-down revealed an uncertainty as to whether all of the non-Class A items had been removed from BSC6.  BSC6's North door had been "hung" with (4) bolts several days ago, as is typical during long periods of in-chamber non-activity, with the understanding that re-entry into BSC6 would occur.  Re-entry was not needed and, days later, Apollo was instructed to install the remaining door bolts to allow us to pump-down the Y-end station.  In order to be certain, BSC6's north door was removed today and, indeed, several non-Class A items were discovered inside.  These were removed.  The door was re-installed after a signed Chamber Exit Checklist was presented to Apollo.