Check if the speed unit connector is loose or dirty. Restart the machine; if it persists, replace the speed control unit. Motor locked rotor
Often related to the synchronizer. Calibrate the needle stop position. Essential Troubleshooting Procedures siruba l818fm1 error list work
Inspect the machine for thread jams in the hook area or check if the belt is too tight. Positioning signal error Check if the speed unit connector is loose or dirty