My hitachis (like in the photo) are going strong after 200,000 kilometers. Very smooth carb. Don't throw it away unless it is broken.

There is nothing wrong with these Hitachi carbs. They are well designed, quite well made & are well suited to their intended application. I have seen them with many hundreds of thousands of of K's on them still performing well.

I am curious to know what was so badly worn on the South African examples that rendered them both unservicable & unrepairable while at 40,000k, the vehicle would have been only just out of warranty.

If what looks to be a broken air filter stud is replaced, & the carb is properly serviced, it will likely give many years of satisfactory service in its intended application.
I suspect that the dud carbs previously mentioned have an owner problem, ... not vice versa.