Grohe Cistern 'leaking'?

I have a couple of concealed slimline cisterns.
They have started to leak water into WC, this is 100% not down the overflow pipe, as water level is well below that.
Took it out cleaned all … still the same (or worse if anything) …. From empty the infill ‘torbeck type’ starts filling, all is fine until around 50mm deep .. and the water starts to leak …. Assuming that the bottom ‘main seal’ is OK, as nothing gets past that initially, only leaks when it get in over the float, so my logic is that is must be getting past the inner seal.

Are these spares items ?
The main seal has No. 14.11.29 1 DAL
The inner seal has No. 14.11.30 8 DAL
If so where can I get them
Picture shows siphon, and the seals in the lower picture.
https://www.mediafire.com/file/p7yqjko0ka1v7ey/Siphon.pdf/file

Sargan
October 2019