Specifications

B) Check that the UTC does not falsely signal the CHECK BOBBIN message when
thread is still on the bobbin.
1. Test for this by simply sewing with the test design. For reliable results,
embroider the design for at least 5 minutes, or about 4000 stitches at
750 stitches per minute.
2. If you get false CHECK BOBBIN messages, slightly loosen the UTC sensor
body at the screws shown in Figure 2-45, and at the slotted screw hole
(left side) move the sensor
a very small amount closer to the needle.
Re-tighten the screws.
2 - 52 Head Section
EMC 10/4 Technical Manual Melco Embroidery Systems