There are different causes which can lead to a performance change of the laser system. Please check the following steps to ensure that the performance change is not caused by an external factor. Please ensure that you measured the output power correctly, (see item 5 above). Please switch the system off completely (including power supply unit), wait for approximately 30min and restart the system. Please ensure that the cooling system is adequate and working properly, (see item 3 & 4 above). Please ensure that all cables are secured properly at the laser head and at the power supply unit. Please ensure that the laser head is mounted on a flat and clean metallic surface with no more than a torque of 2Nm. If the base, where the laser head is mounted on, is slightly bent or if there is some debris between the laser head and the base or if the laser head is mounted with uneven torque on screws leading to a bending of the laser housing, this could affect performance. Please ensure that there are no back reflections of laser light being redirected into the laser aperture. If a fibre delivery system is present; Please check if there is any damage or kinks visible on the fibre. Please ensure that the fibre is not tied to any water hoses as the vibrations of the circulating fluid can lead to a performance change of the system. If the problem persists after completing all checks then please contact our Laser Quantum Support Team who will be happy to assist you. Related to: ventus/gem/torus/opus/finesse