Enterprise Vault Outlook Plugin's Still looking At Old Exchange

Hoping someone can shed some light on this issue, we have a client running Enterprise Vault version 10 archiving a 2003 Exchange. We're currently migrating the client to a 2010 exchange and so far have added this into EV, got the green light from the depolyment scanner and can browse the archive of mailboxes via the Explorer plugin (RPC over http) but the plugins wont archive mail or retreive it, looking at the hidden MSG it's still referencing the old exchange. We've tried manually re-indexing/provisioning the exchanges and have the migration mode reg key set but still no joy.

is there another way to update this (even if it's manually)?

Thanks

Russ