Geberit Rak new style (dual flush) button

[MelancholicPanda]

First of all apologies if this has been posted in the incorrect section.

Is anyone here familiar with geberit flush valve type 240 and its dual flush button? I had much trouble identifying it but thanks to google im 95% sure i have the right one.

My council installed a dual flush toilet a year or two ago and on the second day the flush button mechanism seemed to have jammed resulting in a small flush regardless of which button is pressed. If i recall correctly, the smaller button could be pushed down independantly of the larger, am i recalling it wrong? Now pushing the smaller results in both pushed down.

Once the little button has traveled all the way down, the larger button can be pushed a further 5mm or so.
Does anyone know if this is as intended? Reason being a replacement flush button is hard to come by and the product description says "This button is not compatible with any other flush valve" so i cant simply purchase another style/brand/type of button (i think?)

I got the council to send a plumber round but he said he was VERY sure it was a single flush system, the mechanism of the button is not jammed but was as intended because its not two buttons, the smaller button was a raised bit for "grip when pressing" and that he confessed he had never encountered this flush system (when i wasnt buying what he was saying).

He said the (singular) blue lever on the left of the black "frame" showed it was a singular flush system. The flush button would screw into the white bit at the top. He said there was only one "spoke" when pressing the button, therefore confirming it cant be two buttons and it was just a single chrome button with a bit sticking out for grip and that otherwise there would be two "spokes" (spokes are my descriptors as i cant remember what word he used)

I don't think he was misleading me or fobbing me off to get out of there (hot day today), probably just unfamiliar with these items.

Sorry for the lengthy post. Basically is the button working as intended (anyone familiar with this brand?) and if not are there replacement buttons that'll work with this flush valve?

 

[Welder]

If mem serves, it's the depth the button travels that determines long or short flush. When #2 flush is called for, both buttons often move on different makes of flush mech.

 

[Burger]

Have you tried Geberit technical helpline or Twyford (owned by Geberit)? Looks like a Twyford option wc suite to me.

 

[Ben-gee]

The council plumber is unfamiliar that is all.

It is a dual flush valve, it may not be set up properly for the cistern.

The height of the valve is determined by sliding up the two ‘ ladder arms’ at the side of the valve - this determines whether the button screws in correctly once the lid is on.

Then the blue arm can be clipped on at different positions too, it’s too dark to go to van to check but I think there are well over twenty positions!

If either of these adjustments are incorrect it may not flush properly.

 

[MelancholicPanda]

Thank you for the replies. Turns out the buttons may just be "sticky" resulting in both going down when the smaller is pushed. I was concerned a large flush always occurred leading to a wastage of water, defeating the purpose of a dual flush.
A Geberit replacement button can be bought for £10 but i'm not sure its worth it. Looking at other button replacements it seems the majority are incompatible. I could have sworn the buttons could move independently but as YorkshireDave mentioned above, it seems to be as intended therefore I'll leave it as it.

Once again, appreciate the time and the replies