How do i fix wobbly / loose choke lever on my 3kw generator carburettor?

I have a petrol portable generator. It runs and starts fine but the choke lever has become very loose and vibrates about and sumtimes even jumps off from the vibration of the engine, this means it can vibrate back to the start position instead of run. how can i tighten this or do i need to buy the complete carburettor that comes complete with lever