With your barrel removed and marker/eyes turned on. Take a camera phone and look down into the breech, you should be able to see the eyes light beam, to confirm that your eye harness is not f@#ked. This does work better in low light conditions.
It works on my DM6, so it will be trial and error for other markers, but its the same principal.
It works on my DM6, so it will be trial and error for other markers, but its the same principal.