4040 carb question

[TFF 13]

My 4040 has been losing power under load. I'm pretty sure I've narrowed it down to the governor springs. My question is about the carb...I have a CCKA engine with down-draft, but where the main fuel adjustment is supposed to be, there is a slotted brass plug. Same thing is on my parts tractor carb. I can only adjust the idle?

[720nut 4,225]

It's a Marvel-Schebler carb. Here are a couple of pictures from Service Manual

Hope they help.

[720nut 4,225]

Thomas are you sure it's just a plug and you remove to adjust? I've never seen one in person. Couple more pictures

[TFF 13]

Thanks so much! I love this club!