Cannot wind the bobbin

SOURCE: Bobbin won't wind, do

Hi,
Open the bobbin cover and remove the bobbin from your machine. Examine the bobbin case and make sure there aren't stray threads jammed into any grooves. If you see clumps or strands of thread, remove them with your fingers or with tweezers.
Look over how the bobbin is positioned in the case and whether or not it is inserted correctly. Different machines hold the bobbin in different ways and some machines don't use a bobbin case. Consult your machine's manual for the proper way for its bobbin to be inserted.
Make sure the thread is wound evenly on the bobbin. If your thread has large sections of loose loops sticking out from the rest of the thread, they easily could be causing the problem. Rewind the bobbin, if needed.
Clean the shuttle mechanism and the bobbin case with a small soft brush, such as a make-up brush, and a dust cloth. Remove as much dust and tiny fiber pieces as possible. Resist the urge to blow into the machine to clear away dust, this can send debris farther back into the machine, causing more serious problems.
Oil the movable pieces of the shuttle by putting a few drops of sewing machine oil on a Q-tip and rubbing the Q-tip over the hinge-like turning areas. Do not add too much oil to the machine; one drop goes a long way.
Reload your bobbin into the machine and sew a line along a piece of scrap fabric. Check your thread tension and adjust it as needed following the manufacturer's instructions. The upper thread should never show through the bottom and the bobbin thread should never show through the top.

SOURCE: Why does the needle move as though it is sewing when I wind a bobbin

Unlikely that a belt is broken. It is more likely that you don't have the bobbin spindle fully pushed to the right. Or worst case is that something inside, under the bobbin winder is broken.