I have a Bernina 1630 and experience the same problem. I am another one who controls the thread feed to the bobbin with my finger. For me the big deal with the bobbin is how does it effect the stitches. If the stitches are good, I'll use my finger and not worry.
Dealers are another story. I tend to get cranky when a service provider of any type blows smoke at me. Pocoellie is right regarding what a sewing machine service provider should provide.
Thanks for the thread because I thought my machine was the only wonky bobbin winder. Guess I'll have to pay more attention.
Pat