Leak in passenger side footwell RHD

[Spyderromeo]

I am sure this is a well known problem. I have had several proposal to cure it.

The fault occurred when I turned off the Air con so suspect melt from A/C condenser, it shows up as two streams of water dripping on either side of footwell, and is influenced by the motion of the car on bends.  I have been told that there are drain valves on to tray that collects water when A/C is defrosted. The valve is called the duckbill, and I think from my Triumph days we called it the Phart valves but I bet they are the same, Triumphs being relatively unsophisticated cars were easy to get at, because they didn't have much to get in the way . I have even found a VIN number which after this the fault is supposedly cured. The description I read said they were very difficult to get at. My workshop guy who is off work at he moment, heart plumbing! say's it is easy but you need to get up on a 4 pillar lift and poke something up the tube.

With solutions like this, my hope is  that you guy's have an easy solution. Any suggestions and full descriptions of methods would be gratefully received. 

Spyderromeo