needle size has nothing to do with the frame- the needle size/type needs to be the correct one for the thread you are using-
the problem is probably the thread- sometimes it is necessary to try 2 or 3 different threads before you find one that will work for free motion quilting-
the machine goes too fast for a cotton thread you would normally use for piecing- poly threads tend to be a better choice for machine quilting. and the weight of the thread needs to work with the needle you are using- some eyes are small and will fray and break threads that are too heavy- some are shaped differently-
visit the Superior Thread Company web site- they have free charts showing all the different needles- what they are for- and what threads to use with them and for what....a great chart to have.