Did you try it with putty too?
And what I found on the password recovery site from Cisco is that, maybe this is important..I have no experience with that series..
mportant Notes:
- In order to simulate this step on a Cisco 6400, pull out and then plug in the Node Route Processor (NRP) or Node Switch Processor (NSP) card.
- In order to simulate this step on a Cisco 6x00 with NI-2, pull out and then plug in the NI-2 card.