We know that your “pulse” generated a good burn from your initial post.
We know the cut is weak
What’s a fill “Easter” like… If you start at very low power then raise the power each time as you can in the power scale settings, do things level out in burning power at some point ?
If they do, where…
In the late evening, can you take off the panels that cover the power supply housing and the laser tube location and with the lights out, look for arching (sparks) along the whole length of the cables going to and from the tube, including your mA meter.
In fact try taking out your mA meter…
Did you put it in, or, was it there from the manufacturer ?
Also, if you are lucky enough to live somewhere quiet, you will potentially hear the arching, even over the noise of your chiller, no need for ventilator as you will not actually be cutting anything, just making the tube fire in a cut, fill situation.
If you don’t see it here anything, sparks, noise, turn off the machine, then using a plastic, NOT WOOD OR METAL, plastic rod move all the cables…
High voltage electricity, especially with high frequency can escape from cable to the frame and the longer the voltage supply goes on the more electricity leaks to Earth, the frame.
We move the cables because:
If we move them and we get power back at least we know where the issue is
Moving the cables means now the electricity has to leak and jump to Earth…so we will see and or hear it, again finding the problem.
Do this a number of times…just to be sure.
The symptoms of this match, at least in part, your situation.
In one short pulse, it works as insulation around the cable can deal with a momentary pulse, but as the use time goes up, the insulation “breaks down” more and more electricity leaks, as it leaks, power goes down.
Let’s see ,
Please keep us updated, good luck