Takahashi-sensei HAS indicated that
the Spring Of Drowned Man WOULD cure Ranma.
I have not heard an official reason for it
not to be immediate, but the Guide would have
simply shown Genma at least the correct pool
to cure the Panda curse at the time that they
were first at Juusenkyo if it were that easy.
The best explanations i've heard are that:

	This debate approaches off-topicness, but it does bring up the germane
issue of authorial intentions. From the tone of your explanations, it seems
you're trying assemble an arbitrarily reasonable system under which the
curses work. The simpler answer, and the only one that the manga
consistently supports, is that the curses work in whatever fashion the
author wishes them to work. More precisely, the curses work in the fashion
that will make the story most interesting.

	It's fun to retrofit some rigid system onto Jusenkyo (or onto the logic of
many series), but it fails more often than not because many authors are
less concerned with strict consistency than their fans are. If constructing
a solid set of rules adds to your enjoyment and/or makes writing a fanfic
easier, then by all means do so; that's part of what fanfics are all about.
Just be careful not to label anyone's use of the curses "incorrect" just
because it's unusual or not directly supported by the canon.


______________________________________________________

Patrick McClanahan

Lost in his own meta-hierarchy.

	"We have lingered in the chambers of the sea,
	By sea-girls, wreathed with seaweed red and brown,
	'Til human voices wake us, and we drown."

			-"The Love Song of J. Alfred Prufrock"
				by T. S. Eliot