How can I replace a bobbin winder on my brother sewing machine?

Take it to a sewing machine repair shop, my wife just had one for a Husqvarna replaced parts and labor were under $80.

Here is your Operation Manual

It doesn’t describe how to change the bobbin winder, but it is good to have. It does mention on Page 35 that the machine will not work if the bobbin winder is pushed to the right. As a solution, it recommends pushing the bobbin winder to the left.

You can ask this same question to Brother Technical Support HERE