When you look into the engine bay you can see a black shaped section of plastic sound proofing located above the engine fixed to the scuttle below the windscreen
there are three bolts holding this in place, one central and one at either end, remove these
now the scuttle tray will pull out
it will need wiggling and twisting to get it out in order to miss the coolant bottle and engine shrouds etc
with this out the way you can now gain access to the drain holes
located in the rear of the scuttle are behind the top mounts
if you dont have the sponge filters? you just need to clear the majority of the debri out of the drain holes and see if they flow any better?
the drains empty into the area behind the wheel arch liners, the drivers side one on petrol models is covered by the carbon canister
v which means it's prone to blocking more
I find that blowing them out with a hose helps to keep them clear