All four drains for my 2000 c70 convertible are clogged.

Access to the rear drains are accessible when the top is approximately halfway down. The drains are round 3"-4" black disks withe many holes. I was able to gently pry out the center disk leaving the rubber housing in place. I vacuumed out all the debris with a shop vac by placing the hose directly over the opening. Tested with water and works good. Still have not figured out how to get to the front drains.

Access to the rear drain is also possible from the trunk (m 2001). In the opper left en right corner (roof) of the trunk you will find (behind the covers) on each side the pipes. Make the lose and clean with aircompressor. Thight them up real good after cleaning.