this has been covered many times before, but I do have to ask: exactly what or better yet how, are you expecting to complete this repair with the carb in place....upside down, standing on your head, in the dark recess up in there, blindly....and what transpires with the other 3 carbs, that are likely in no discernably better condition, just have'nt givin outward failure symptoms yet?
I highly suggest pulling them, and doing it right.
all 4 of them.... you are only fixing this 25% by the attempt, and are setting yourself up for a soon to be further saga.