Hello mate. Could be a few things: 1- Take off the shutter spring and tape the shutter so it doesn't effect the laser.Even though the shutter looks like its ok, it can still give problems. I left mine like this and never had a prob since 2- Check reg clutch, sometimes it shorts and goes to ground. You will notice straight away if its worn by the dust. 3- Check dev units connection to the hvt face. Its sprung loaded so clean faces and check spring. 3-Right laser? Had it when a enginner put a 2270 laser in machine but swapped the motor so connections were right!, worked for a bit then failed