Leaking fluidmaster side entry concealed cistern

[elmag28]

Dear all,
The fluidmaster toilet is continuously leaking into the toilet pan. The push button is completely floppy and has no resistance.
I removed the lid and it seems the inlet valve is letting water in continuously but it does not reach the outflow pipe but is about an inch high.
Am I right in thinking that the flush valve is broken?
Can it be repaired or replaced easily. We do have a screwfix and toolstation closeby.
For now I have closed the inlet valve.
I will be grateful for any advice. I have attached pictures of the mechanism.
Many thanks,
El

 

[terryplumb]

The flush valve / it's mechanism needs repair or more likely replacing . If you release the cable from push button mechanism ,then rotate the flush valve it should lift out . Take pics and we can advise further.

 

[elmag28]

Please find attached the pictures of the flush valve. There's bit of limescale on the bottom part.
Thanks for your prompt reply.

 

[terryplumb]

The pics are not clear ,but examine the SEAL ,and the mating surface that it sits on inside the cistern. If they are not in perfect condition you need to renew .