Fuel bladders

After sitting for many years with empty tanks (ouch), a friend of mine is
restoring a very nice Navajo Panther 310. Unfortunately, today he tried to
put fuel in the inboard right wing tank and it started leaking, first from
the panel around the fuel quick drain, then from further inboard. An IA has
looked at it and it looks like its coming from the hose running down from
the bladder and into the fuel lines. I've been told these bladders are
likely to develop cracks and leaks if left dry for long periods of time. I'd
like to help my friend with some homework. What are the chances of getting
this bladder repaired? Recommendations on where to send the bladder for
repair? Gotchas or warnings gained from prior experience that anyone would
like to share?

Juan