Old Grohe mixer tap knob removal

[Old UKPF 70735]

I need to replace the washers on this old (1980s?) mixer tap.
Can anyone tell me how to release the knobs on these? It looks like a 4-way spring-action plastic clip and I can't feel anything like a screw in the bottom of it.

Many thanks.

 

[waddycall]

Just guessing but what about pushing socket or suitably sized piece of tube onto the tapered ends of the plastic clip. Might push all four in at the same time so you can slide the knob off.

 

[Shower Engineer]

It just pulls off but it needs to be pulled really hard.....

 

[Old UKPF 70735]

Thanks for the suggestions chaps. I've pulled hard but there's no budge. I wonder if I need to make up some sort of pullers?

 

[Best]

I suggest you try squeezing one or two of those plastic clip parts using pliers or similar, while gently pulling the tap head out towards that side