Hello and welcome to SBB!
Some of the older tutorials images were lost when our web servers building had a fire and they weren't on any of our actual computers to restore them.
I know that Shelleyrae has gone through and replaced/repaired as many as she could. Other then that if you find one in particular we can look at it and see if it is a tutorial that we hadn't check yet and if we have the images we can replace them, but chances are they are gone.
If you are having trouble understanding a certain tutorial PLEASE post your questions in the fourms here along with which tut you are trying to do and users here will be more then happy to help you fill in the missing pieces!