I think you just need to know what your firing threshold is, and keep Min Power at or above that, so the ramp is consistent. Glass tube CO2 systems have a few well known idiosyncrasies, and this is one of them. It takes more energy to fire the tube than it does to keep it firing. There’s a setting in the Machine Settings called “Engraving Mode”, and setting it to ‘Special Mode’, if I understand properly, gives the tube a little high-power kick at the beginning of each L-On transition, which allows higher wattage tubes to fire at lower power settings. Might be worth a shot for you, but I believe it also consumes the tube faster - worth looking into.