Bicycle repair help

I am such a stupid. 

I'm doing some long overdue repairs to my boy's bike.  I've left it to him and a few things have become, well, let's just say beyond optimum.  It's a street BMX, I can't remember the size, 20" wheels.  I'll dig up more info if necessary. 

Here's my problem.  Rear brakes.  Things are much different than they were when I was a kid.  Cable runs from lever to some sort of splitter.  Two cables come from it, down to the headset and into a traveling disk.  Two other cables come from the disk, run down the frame into a reverse splitter.  One cable comes out.  This connects to a little piece of magic which ends up pulling a ribbon shaped length of cable connecting to the brakes themselves.  I know that makes no sense unless you're familiar with this setup.

I just can't get enough leverage on the back brake pads.  They're riding a 16th of an inch from the rim but something is hanging up the pull.  The levers are new, that's one of the things I replaced, is there any chance they're the wrong size/type/something?  Any ideas?  This chit is driving me nuts.  Been out there for three hours now while the boy fecks off to the movies with Grandad.  Grrrr.

I'm pretty handy with bikes (having ridden and worked on them for almost 30 years), but the setup you're describing is like some sort of foreign frenchy type cheese-eating-surrender-monkey language or something. Any chance of attaching pics?

Maybe tomorrow.

At the moment I'm jonesing on a serious, "All I need are some tasty waves, a cool buzz, and I'm fine." vibe.