Control knob loose on 1.5 bowl kitchen sink - Please Help

[portlanders]

We have a 1.5 bowl kitchen sink with a pop-up waste in each bowl and control knob at the front of the sink.

The control knob has come loose including the base that it sits on, meaning it's moving around showing parts of the hole in the sink.

I've been trying all night to figure out how to fix this back in place, there is a large nut under the sink but tightening that doesn't tighten the control knob to the sink, just mean you cannot raise the control knob... if that makes sense? The control knob is attached to the waste by a cable.

It seems to me there should be another nut under the sink to fix the control knob to it, but i've just run out of ideas. Can anyone please help me?

Thanks

 

[portlanders]

No need for any advice now, was obvious it was broken - see b&q do the unit for £20, but for a quick fix i just took it off and placed a tap stopper over the hole in the sink.