Is she using a thread net on the thread spool? The pacesetter embroidery machines seem to behave better if they have a net on them. Is the thread breaking on the top or the bottom of the work? My 6500 has a nasty habit of breaking on the bottom. If there is the slightest bit of thread in the thread cutting mechanism it will cause all manner of grief. The fix is to remove the needle plate and clean it out.
1: Remove the needle from the machine.
2: Remove the needle plate.
3: Turn the machine on and press button to cut the thread. Watch the mechanism. If you miss it, press the button again.
4: Make sure there is no thread between the upper and lower blade. If there is, GENTLY lift the upper blade just enough to brush the thread out of the way, use a needle or a pair of tweezers to move the thread.
5: Since you have the needle plate off clean out the lint in and around the bobbin area.
6: Reassemble the machine until the next time.