First have a look at this sites sponsors web site for a parts breakdown. If nothing is forth coming, have a look at a mercedes dealers parts web site in south atlanta. It should show a steel and glass roof parts breakdown.

There should be rubber hoses in each corner of the sun roof tray to drain water. One may be cracked or plugged. When replacing the headliner on Moms 97 C 280 I replaced the hoses as well, they are $ 15.50 each retail from MB. I tried to find the correct ID and wall thickness but noting was forthcoming from my industrial hose vendors.

I had looked at changing the glass roof on the C280 to steel to reduce sun load but found an entire assembly would be needed. None were in the local area so I covered the inside with white vinyl.