The 15W laser that I added on to my CNC kit abruptly stopped working mid job. Can anyone recommend how to troubleshoot the laser and its signal? Or are these disposable? I've been using it for engraving my logo onto some products, and over the course of use (6 months) the power did seem to get weaker and weaker and I started running the jobs slower and slower, and it would now only engrave on darker surfaces. Now the laser does not engrave at all, and the small focal dot has disappeared. Thanks for any tips/recommendations. Does anyone know the approximate lifespan one will get from these lasers?