Correction. The problem is not that the CarterBrocks need tuned. It's how difficult they are to tune. And how difficult they are to find parts for and information on how to tune them. The OP talked to the manufacturer straight on and they blamed someone else for their problem. Either they didn't know they had a problem or knew it and hid the info. Which one is worse?

Here it is 2021, this platform carb has been around over half a century and the fix for a common problem that people have been dealing with for decades is still news to many. That is the problem.