gene i can understand your pain. one of the reasons that i don't necessarily like sudo systems.
one of the first things that i do when i have a sudo system, ubuntu, lmde, raspbian, is to 'sudo su' and then 'passwd' to actually set a root password. i have found that this has remedied the situation that you have described here. with doing the above you wouldn't have to mount the sd somewhere else, you just make a new password for root. i hope that this helps some for future reference. take care em