We may have found other answers which could help you.
Click here for Leak Cistern Seal
Toilet Push Button not flushing properly?
GroheEAU2 Dual flush cistern. The large flush button keeps breaking off?
Grohedal flushing?
How do I remove the fitting for the flush on my hidden cistern toilet?
Short burst of water entering cistern ?
how do I change the bellows in the push button unit for the grohe cistern?