There should be scalp plate on the strike side of the door.
Remove the scalp plate, usually held with 2 very short screws- be
careful they are hard to come by and they are very short.
you should now see a set screw that lines up with the cylinder.
Back this screw out a few turns and screw your cylinder out.
Notice on your new cylinder that there is a groove cut in the side
through the threads. This groove is what the screw grabs.
Keep the whole world singing . . . .
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