wheres the leak

This leak is somewhere in the area of the scupper. Showing up 4 floors down. No attic space.

That's alot of floors to bypass without showing any leaks. Run a hose right up into the scupper without getting any water in the gutter or on the roof and see if you can recreate it. If not, run the hose in just the gutter, and if still nothing saturate the pipe.

BTW, I like the pipe as #1 suspect.

What's with all the patches in the BIG? Are the joints sweated, of just 'front-soldered? How far do the slate lap into the gutter?

Need pix. :)