I think we need to stop & re think this.
I purchased another mower which started up fine & throttle lever did what it was supposed to do.
When home i used the purchased engine in my mower with my carb. Started up & High revs. So I then used the carb that was on the purchased mower but still high revs.
This tells me surely it can’t be the governor as it’s the same governor that was on the engine that I viewed & bought & worked fine.