Lawn Tractor Question

I took the carb off and ran a strand of fine copper wire through the openings in the jet. There is a screw in the side of the body of the housing under the float that i assume keeps the jet from moving. I removed that screw and attempted to unscrew the jet. The jet has a slotted opening in the middle of it that is accessible from the bottom of the float bowl. I could only turn the jet about 3 turns and it got really tight. I did not want to damage the jet so i just eased it back in to the body. I just cannot see any particles in this carb, It looks completely clean. It just will not keep running.