I have had a few drips from the bottom of my cistern (where it joins the pan). I have a close-coupled cistern. the wing nuts wee originally so stiff and i couldnt get them off for a while. then when i replaced them looser, water would drip every time i flushed the toilet. I tigthened then pretty tight and it was only drips, but the problem is ... I have tried to replace a donut washer. The standard 1.5 inch size. But when it's on, the cistern won't fit into the pan properly. Are there different size donught washers?? Also, I have replaced the wings nuts and screws and washer. I have tightened them pretty tight and they still drip a little bit, hardly anything though. BUT is the problem a split donut washer or what else coulsd it be???