remove the grill below wipers.
This is what I managed to do as well. Just removed enough clips to allow me to bend up the scuttle to clean out the well. I'm actually thinking of snipping one "cross" out of each grille and fitting a plastic plug into the hole. I could then remove the plug and get a cleaning tool, even a small flexible bottle brush, into the enlarged hole to allow me to push any build up through the drain hole without dismantling anything. It's a long shot but it might just work...The grills have small plastic grommets, turn the screwdriver slot a quarter of a turn then pull upwards, they should not need removing though, use a wire or thin bladed screwdriver through the grills.
No need to remove the wipers.