If it's a pneumatically operated dual flush system, the small dual exit air valve behind the button is prone to problems which can lead to only the small/short flush functioning.
Again, for pneumatic it's just also about possible that one of the tubes has detached.
Conventionally, the panel with the button mounted is a clip fit, which will pull forwards for removal if you get a thin object under each side.(Test one side carefully for movement).
|