bing 48 question?

[david newbie]

I recently found an old beat up non running 038 (think it's a magnum probably) with a Bing 48 carb. THe metering lever is a red nylon piece that seems to be non adjustable? So I assume there is nothing i can do with that adjustment. There also appear to be 2 slotted screws in the fuel bowl area under the diaphragm, andy idea what those are.? I rebuilt the carb and it starts but idle is all over the place , and seems to eventually die. Have not put a bar on it yet. sorry, no pics