bobbin winder
please remember that when the large toothed wheel on the bobbin winder is adjusted it will move the said wheel closer or further away from it counter part on the wheel spindle. there should be some slight play or looseness between the two teethed parts or it could break of said teeth on the wheel or make it harder for the tyre to turn. when the correct setting is found tighten the nut on the bolt to hold it in possition ,then the wheel can be adjusted to have light presure on the main balance wheel.
hope this helps as i am not good at explaining things.