Small Engines (Lawn Mowers, etc.): air-fuel adjustment screw, adjustment screws, adjustment screw

Question
My Craftsman mower with a 21hp B&S does not seem to have any air-fuel adjustment screw. Did they quit providing them or hide them so the owner will not be messing with it? I have seen adjustment screws hidden under a cover that could be pried off, but not on this one.
The engine is surging, but runs ok with the choke pulled out a little. I replaced the air & gas filters and put a new fuel pump diaphram in the carb. No change.

Answer
Most of the newer carbs do not have any adjusting needles at all due to emmissions control regulations.

Have you removed, dis-assembled and cleaned the carb with compressed air and carb cleaner?  Carb cleaning typically solves surging problems.
Eric