CGail

There is a problem with the way the bobbin winder was installed.
There is a screw with two washers that holds the bobbin winder in place if you are missing either one of them you will not be able to tighten the screw enough on the bobbin winder to give you enough tension on the bobbin winder for it to turn.
One of the washers goes on the screw first then the screw is inserted inside the hole in the bobbin winder the flat washer goes over the threads of the screw insert the screw into the threads on the machine and tighten it tight you should have sufficent tension now to operate the winder when it is engaged to the belt.

MFord

Mine didn't work when I first got it, as the bobbin wheel wasn't fully contacting the belt. I ended up removing the handwheel and moving the whole bobbin winder assembly just slightly to fix the problem. I also cleaned and oiled everything thoroughly. You might have to get some Liquid Wrench or similar to get that frozen screw moving. Or just oil the area and let it sit a week or two, then the screw may turn.