Hi Scott!

Basically, you "just" have to remove the trim curves from a surface to regain the original surface. But this could get quite tricky, depending on you setup.
There is a (dated but valid) tutorial on object repair techniques available.

http://moi3d.com/forum/index.php?webtag=MOI&msg=446.17

~
Marco

Scott,
In most cases, you should be able to delete any interior surfaces you created, then select and delete any naked edges. That should restore the original solid.
(Naked edge script here, if you don't have it: http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2)
Ron