I have had a similar experience with this unit so I suspect it is a design or quality issue. A few months after installation I notice that it continuously drips particularly after a short flush. The only way to stop it is to do a firm press of the long flush button.
So, the question I have is, is there any way to adjust this. Sykes suggest putting in a whole new kit but given these are new units I'm not sure this is the right answer. Maybe it should be fixed under warranty.
Vince
May 2011