Need help on W210 washer fluid tank removal

[ProV1]

My washer fluid tank leaks but I cannot seem to locate the leak. i cannot see fluid coming out from the sides, I think it's leaking from the bottom. however the fluid stops leaking when there's about 1/5 of fluid left?? almost makes me suspect one of the pumps/hoses is leaking.

i tried to remove the main tank but after removing the 10mm bolt, it still won't come out. how is the tank removed? i do not want to order a new tank ($35) without knowing what the real problem is. also, the tank has tons of different connections and hoses going in & out... this is a 2001 E55.