I am guessing this is a CO2 laser? the very first things i would check for are evil dust bunnies that need to be slain, second is the thermistor used for sensing temp and 3rd checking the capacitors for swelling, over heating or leaking, most items act in a random fashion is any or all of the above happen, other then that i know nothing of this laser
oh and sighns of heat stress, discolored parts with the board under being discolored or ring cracks on the solder, use magnification for that
Remember Remember The 8th of November, When No One Stood, but Kneel, In Surrender
In a popular government when the laws have ceased to be executed, as this can come only from the corruption of the republic, the state is already lost. Montesquieu