Headlight lifting motors-manual knob

The knob to manually raise the headlights rotates, but does not raise (either) headlight. Is this common/easy fix, or a complete strip down of the motor assembly?

 

Thanks both. I turned it a lot! It doesn't feel as though it is turning what I presume is quite a "strong" motor, more just spinning. If it's just a plastic knob on a hex on the shaft, I wonder if the hex has "worn".

I was changing the headlight bulbs and more by luck than judgement put up the lights and then disconnected the battery earth.

 

When working does the knob rotate as the headlight buckets comes up/down?

 

To conclude:

I didn't fully understand "a lot"! With Grandson at the controls I watched the knob spin "a lot" as the headlights lifted. I hope I never have to do it in earnest in the dark; I reckon it would take 5 minutes to lift each light!