In version 4.42, the stitch regulator was found to have this problem.
Check the motor ratio
1. Go to Folder -> Diagnostic -> Motor Settings (password:motor) -> Additional Settings
2. Click on the motor ratio number. If it is not 1.475 or around there then it is the problem and will cause a runaway condition.
3. Select the Motor Ratio button (Nothing will happen after this button is selected)
4. Turn the hand wheel a few times counter clockwise
5. Tap on the “Motor Ratio” number (Not the button) and verify the number is about 1.475. If not repeat steps 3 and 4. 6. The problem should be corrected. Try you machine and verify it is working correctly.