problems with single flush button toilet

[mogsie]

I have a single flush button toilet and the flush had become very weak ( ie only a small amount of water comes out ). I wanted to have look in the system but the top is tightly secured and wont move. I have seen how you get the dual buttons off - but this is a single button which I am struggling to remove ( have tried to screw to no avail ). Please could anybody tell me how I can get the lid off and then what the problem may be ? Thanks

 

[footprints]

Any chance there is a screw under the button? Maybe a bit if Blu-tac or tape stuck to the button and pull to see if it lifts out.

 

[mogsie]

Thanks -There is an ring surrounding the button which I can't get off and don't really want to try and force it.

 

[HERTS P&D]

The ring doesn't come up, use a small screwdriver between the button and the outer ring to prize the button up. Under this you will find a screw.

Post pictures.

Andy