Air fuel ratio control CAT 3408

My Caterpillar 3408 has suddenly started blowing heaps of black smoke when I put my foot down, meaning that the air fuel ratio control has stopped working. It may have blown the diaphragm, but it also may just be sticking. I can't remember which way you adjust the screw to give less smoke. The control is the type that is air operated.
I'm a long way from a CAT dealer, otherwise I'd just buy a new air fuel control, but I still have to adjust it.
Help please? As far as I know it's the same control as a 3406.

 

I'm pretty sure one of the screws gives it more fuel and another one adjusts the delay from when the turbo spools up. I had the same trouble a few years back and I put a new air fuel control in, it didn't cost much. Back then I used the CAT online manual which explained everything, but I can't seem to get hold of it now even though I'm still registered with CAT's SIS system.

 

I'm still unloading at an iron ore mine called Tom Price in the the North West of WA, so it isn't fixed yet. I've got to stack my trailers up and go to Perth, just under 1,000 miles away but I can feather the throttle to a certain extent and anyway there isn't much traffic until I'm about 100 miles from the city. I don't know if the AFRC is stuck or I need a new one, but I know it's a pain in the ### to adjust just right. I think I'll wait until I get to Perth before I look at it, and I'll time it to get to the city at night.

 

Well, I fixed it. I bought another air fuel ratio control off this engine. Expensive air fuel control because I bought the engine as well.

 

I've already got one. It'll eventually probably go into my KW. Bolt straight in because there's already a 3408 in there. The engine I bought needs a full rebuild which I'll do when I've got time, no rush.