My uncle put in a fluid master fill valve for my mother in law. The problem after a few days is the toilet tank doesn't fill up enough and the pressure when flushing is weak due to a lack of water. I believe the fill valve needs to be adjusted about an inch higher.
Is there any way I can adjust it with out taking fill valve out of toilet? I reached in there and tried to twist it but am scared of breaking it. Also they say you could raise it by turning screw clock wise, but that also doesn't work.
This is the fill valve