Small Engines (Lawn Mowers, etc.): B&S engine stalling, starter clutch, red arrow

Question

Carb photo B&S model 130292, Type 0159. When I started my tiller this year, it made a loud screeching sound. I replaced the starter clutch which took care of that. Now I'm trying to figure out how to keep the engine from stalling when the rotating tines hit the dirt. It starts ok, and when I push down on the handles to lift the tines of the ground and put it in gear, the tines turn ok, but when I lower the tines to the ground, the engine slows down and sometimes stalls. The photo points to two adjusting screws, but I'm not sure if one or both should be adjusted. I tried adjusting the screw with the red arrow a little, but this didn't seem to help. Should one or both screws be adjusted, and if so, how much? In the photo, the air cleaner is removed. It is a pulsa-jet carburetor.

Answer
Jerry

The red screw is for the idle control that gets adjusted after the carb smooths out.The yellow screw is the main adjustment turn that one till it is closed all the way,do not force it or the end of the needle will be shot.Now turn the needle 1-1/2 turns out that is a neutral adjustment to get it started then  you can fine tune it by turning the screw. If that doesn't work it is time for a rebuild by the looks of all the dirt around the tank and carburetor. Is the air filter clean? Is the gas fresh? Make sure they are.