Manufacturer assembling based off memory, not the work instructions

TLDR: manufacturer won't follow manufacturing steps and instead goes off his own memory which leads to many mistakes. How do I ensure quality during this build?

Well. I'm at a loss here for how to handle this. The worker who is assembling my product is completely unwilling to follow the steps outlined in the work instructions because he feels he already knows what to do.

Problem is, he is always wrong and he has been wrong in different ways on every single test build I've done with them. The work instructions are completely detailed with text and pictures so that is not the issue. He barely speaks English so I'm assuming he can't really read and thats why he just goes based off memory rather than trying to use the document.

How the hell do I ensure my product gets built properly? I've built it myself in front of them, I've stood beside them and let them build it while I correct any mistakes, I've gone home and just let them do it themselves. Issues every single time.

Only option I see right now is me hovering over them the entire time (awful solution), or getting someone else from this same manufacturing company to do the assembly (might still have the same issue?). They are my only local option and that is very important as it makes finding these quality issues early much easier. Appreciate the advice..