Ceramic Valve replacement search

[Old_Brown]

I need to replace 4 ¼ turn ceramic valves for a second hand kitchen tap set - two taps. The current ones are dripping. These are marked X17C, and have a threaded collar. I've been to two local reputable plumbers merchants with the old valve and the head and cover to assist in fitting. No-one has been able to give me an exact replacement and this size does not appear in any of the sample boxes or online guides. One likely replacement, CC7, has too much depth, so that about ¼" of copper shows when the shroud is put on, but is otherwise correct for splines. Nothing shows up online and any serious seller has the same range of sample sizes as carried locally in-house. Any ideas. or does her indoors have to resign herself to dripping taps?

 

[snowhead]

What about just replacing the ceramic discs and seals?
It may only be the seal on the bottom of the valve that's allowing the ceramics to pass.