Charlie is right, the rubber seal/diaphragm is probably shot. You can remove the slave and have a look. When I recently removed mine, I glad that I wasn't going to have to bleed the clutch afterwords (the seal prevents air from getting in - that's why you remove the whole slave instead of undoing the line when you need to drop the bellhousing); however, once I removed it I realized the seal was bad and a little fluid was dripping into the bellhousing (hence the leak coming from the bottom of your bellhousing). I have a new one, but have yet to install it. Good luck.

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'95 E300D ("Tank") - 231,000 miles
'79 240D ("Biscuit") - 197,250 miles (Sold)
'83 240D ("Ding-Ding") - 217,000 miles (Death by deer)
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"Back off, man. I’m a scientist” ~ Peter Venkman