Trying to replace Roca dual flush rubber washer

[Scarum]

I'm trying to get the white end piece off this Roca toilet flush assembly. Is it supposed to click off or twist off? Either way it won't budge!

Btw I removed the leaking rubber wasjer already by cutting it, I thought it might help in getting a grip...

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[longdogs]

Does the new washer not just push over it?

 

[Newboy]

After turning 90 degrees, it pulls off but may need a bit of leverage!

 

[Newboy]

deleted

 

[Scarum]

After turning 90 degrees, it pulls off but may need a bit of leverage!

Finally some water pump pliers got the thing off, new washer fitted and all working normally now.