When you unscrew the screw the pliers will hit against the toilet bowl and prevent the nut from turning and it will loosen.
Toilet lock nut clockwise.
The lock nut threads onto the fill valve inlet just above where the water supply hose or tube coupling attaches.
Remove the fill valve.
I then would proceed counter clockwise with a second offset 6 pipe wrench and try to loosen the nut.
Gently pull the nut down.
Step 3 replace the valve.
Using various methods to remove the nuts and the bolts when the toilet bolt won t tighten gets your project back on track.
Use your pliers to loosen the nut under the tank.
Raise the pipeline from the overflow tube.
If the nuts don t have wings lock a pair of locking pliers around each one in turn.
Remove the nut washer and lock nut.
Tightly secure the lock nut washer and nut.
The valve is connected to a rubber ball float.
These are used in a toilet chiefly to secure the fill valve in the toilet tank.
Empty the bucket and place it underneath the water supply line.
Then finish loosening the nut with your fingers.
Use a pair of pliers to just loosen the coupling nut.
Position the new valve in place of the faulty one.
Lock nuts are used to hold fixtures securely in place from below.
Locate the coupling nut on the underside of the toilet tank.
The end of the water supply line will come away from the connection.
Some nuts have wings that you can grasp with your fingers.