I have a 1662 singer sewing machine and i can not get the bobbin thread to thread to top thread. I have cleaned machine. reread manual to make sure bobbin is thread correct and also that machine is threaded correctly. All are correct I loaded the bobbin it will not catch when i rotate the needle. It always did before now it just does nothing what i notice is the case doesn't rotate any more. It is a plastic case.

Please help