Try injecting in the air- if everything is ok, make sure the operators are pushing the injection head all the way into the bird and not continuing too fast to the next bird (can happen when injecting at a fast speed, especially injecting on a carousel).

Make sure the mode setting on the Control Unit is set to Automatic.

Make sure you have an automatic Injection Head assembled on the Hand Unit.

Make sure the needle hub is not preventing the injection head from retracting all the way back.

Replace the injection head with a different automatic head.

Press the trigger and check if the flashlight turns on.

Replace the injection head with a manual injection head and switch the setting on the control unit to manual. If everything works ok with the manual, continue to step 8.

If the flashlight does not turn on and the manual injection head is working ok, the issue is probably with the Hand Unit's Automatic Injection Head sensor. It might have got damaged. Please replace the Hand Unit.

If the flashlight does go on and or the manual injection head does not work as well, continue reading here.