Just trying to gather some info and it's a long shot if you can't browse through the system to check default values, but is there something to be found in the 3300 logs as to what time they (I assume) drop out and ask for pin?
Are your general Cluster settings and ICP/PBX Networking settings correct under Trunks -> IP/XNET? e.g IP's matching the ICP number on all cluster nodes. I have once seen weird things happen due to the fact info was entered incorrect there during a migration to a cluster.
Dutch