Sunroof Leaking & Drain Holes Are Not Clogged

[1-cophere]

Hello new to this forum. I have a 2000 GS300 and I'm getting a leak at the top of the Pillar Post on both sides. I pulled off the Pillar Post and checked the Drain tubes and they are not Clogged. I ran water down the front tubes and they drained perfectly. I pulled down the front of the headliner and noticed a Plastic piece and it looks to have a piece of Copper Tubing running under the Plastic piece. When I ran more water and it ran across the front channel, I noticed that the plastic piece, that you can only see with the Front headliner pulled down was leaking, causing the water to run back down toward the Pillar post and exit (water) at the very top of both Pillar post.

Any suggestions? What is this piece called and can it be replaced?

Thanks in advance