we usually use the SNMP-Copy-Method for saving configuration to a tftp server.
Last week we installed a new 876 IOS 12.4-15 T1. Tried to copy the config via snmp and it failed. Checking the oid's showed that the OID-Tree 184.108.40.206.220.127.116.11.96 isn't there! Any other OID works! Why? Any suggestions?