Singer 14T967DC Workbook page 83

Install the Knife Cover.
Engage Upper Looper. Engaging the Upper Looper causes the looper to move
when sewing. Even though the Upper Looper is not threaded it needs to be
engaged.
1. Push the clutch button to the left and down to engage.
2. Turn handwheel.
Upper Looper Disengaged
Three-Thread Flatlock (narrow) page 7
Upper Looper Engaged