Grohe concealed cistern, have to hold button down to flush

22 Jan 2009
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United Kingdom

I have a Grohe 38690 cistern and you need to hold the button to flush and it flushes slowly. It looks like I have the flush valve 42774000 with blue air hose.

I've removed the button (part 42357p10), when I put my finger over the air holes and press either button, i can feel resistance so it seems like the bellows is not leaking.

Not sure if relevant, but my bellows assembly has the green indicator on the larger of the two cylinders, however, the flush only works when then blue pipe is connected to the unmarked smaller cylinder. Pictures online have the green mark on the smaller cylinder.

Can anyone advise what I need to replace to fix this as the parts are expensive and would like to get it right first time.


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