help with slow archive please

Hi, Doing onbar archive to Tivoli 5.3 with IDS 10.0.UC5 on aix5.3, to a 3490 tape library.  All of the sudden our archives are taking much longer. Don't see why, and am trying to Troubleshoot. Our onstat -g iov is looking good. I remember that there is an onstat -g stq, that will show what's going on between onbar and the tape drive etc.., but am not sure how to interpret that. Can someone clue me in on it ? I guess it's between whatever is in the fullqueue vs the empty queue, and waiter status ????? Thanks, floyd