Thanks for the eyes-on look offer for the 5030, but I have it covered with the diagram now. The part that is leaking is attached to the HST regulator/pipe and is called a joint pipe, part #TD060-58280. The dealer suggested that I go ahead and replace everything there as long as the system was going to be open to prevent a re-occurrence in a short time elsewhere on the connection. He indicated that the leak was most likely caused by vibration which over time likely cracked the pipe.
I am getting a new pipe (TD060-58270), a new joint pipe (TD060-58280), a new joint (TD060-58290), and two new o-rings (04817-00110). Total cost less than $60, but while I am at it, I am going to be changing out all the hydraulic fluid and filters, so that will increase the cost into the $300+ range.
The good news is that the dealer is going to try and claim the parts (and maybe the fluid/filters too!) under warranty, even though I am a week out of warranty technically. The warranty doesn't cover the pickup and dropoff of the machine, though (a $150 service) and since I don't have anything capable of hauling the tractor, I'm just going to do the work myself.
Attached is a pic of what is being replaced. It is noted as 130, 140, 150, and both 160's. It should be a pretty straight-forward job.