Final answer:
The technician should insert a new light blue-topped tube to see if it will fill.
Step-by-step explanation:
The technician should insert a new light blue-topped tube to see if it will fill. The slow or incomplete filling of the light blue-topped tube indicates a potential issue with the blood coagulation process. By using a new tube, the technician can ensure that there are no obstructions or clots in the previous tube that may have hindered the filling process.