02 CXL Leaking Sunroof

The headliner in my 02 CXL gets wet to the point of dripping when it rains, or the snow is melting on it. One autoglass shop said the sunroof is designed to channel water to two drains, one in each "A" post. He blew them out, and all seemed well. But the problem is still there. I have had my own try at blowing out the drains, and I can get the water to flow, and then it seems to slow down on the driver's side drain. Repeated attempts haven't made things much better. Has anyone else had this problem, and if so, were you able to fix it for good? Thanks for anyhelp you may have. Perry