this is my first post ever, I guess. Actually, I might have already registered some years ago but I eventually forgot username and password

I've picking locks for years but, in truth, I'm still a beginner. I used to start off picking and after a few weeks I always gave up, and this happened many times. Probably, if I had made it to pick the padlock in subject I would have moved on picking locks more often. By the way, it's the original italian corbin padlock.
Now, for a few days I started over again and still managed to pick some new locks. But it seems I will never get my corbin co. 50 mm opened. I feel I'm close but not close enough. Please have a look at it:
http://imgur.com/a/i39Ne
As you may see, it has a very narrow keyway. For this reason, I tried also to use a top-of-the-keway tension wrench. This leave me far more room. Soon after I get the false set I can set some security pins, as I can see the plug rotating into a, let's say, bigger false set. However, I alwyas get stuck when, at some point, a couple of pins are yet to be set (also, I can lift them easily as I wasn't rotating the plug) and I can't feel any other couter-rotating feedback.
I know from the key that the fifth pin is far shorter that the fourth, so I fear I might be oversetting some pins while picking it. But basically, I can't go any further.
I wonder if you guys have ever got the chance to play with this padlock and may be willing to give any advice...
Thank you all again.