Geberit hidden cistern small leak of water from cistern to the pan

A small leak from the cistern of a Geberit hidden cistern system.
The cause was an old rubber seal which you can sometimes clean but often need replacing.

[@jamesmonk5916]

Brilliant, great to have a guide on the older model. Now fixed ;)

[@elohman1956]

To fix leaking, consider putting the silicon rubber valve between papers under a warm iron for a few minutes.

[@molotour]

i have the same cistern but changing the gasket did not fix my weeping leak. Im scratching my head now. I cleaned the rubber washer on the cylinder as well. Any ideas why it still leaks ?

[@molotour]

The problem was the rubber basket seal. I ended up buying a new flush valve on amazon. These phantom flushes are a real problem, so much water wasted.

[@losamarillos88]

Whats the ring size that you need? Thanks