IH 4 cylinder motor speed fluctuating, then stalling - needle and seat?

Looking for seasoned advice, for what may be a simple fix?

 

Took my IH 230 swather down on steep, treacherous hill, to access low ground to mow canary grass...and when I was (trying) to barrel-through a low, wet spot, he began sputtering and immediately became mired in the clay.  I winched it back out, but I am stuck in a different manner, because now I don't trust it to back up the narrow path up the hill (deadly, precipitous drop off on one side, mature trees to roll back against on the other side if he acts up)...

 

Occasionally, I have to tap on the carb to get it to run/start, and it seems to be a needle and seat problem.  I am suspecting this may be causing the fluctuation problem too, causing the governor to move back and forth rapidly, as perhaps it is getting too much gas(?).

 

Can a guy pull these two out together, without removing the carb?  Perhaps it is just gunked up?  Can I purchase the two as an assembly and install without buying a carb kit?

 

This seems to occur when the engine is warm, and it runs well when cold…Am I on the right trail here with the needle and seat/carburetor?

 

Thanks for your advice!
Mark

IH 4 cylinder motor speed fluctuating, then stalling - needle and seat?