Do any of you have experience with the smaller cnc lasers?The controller specifically

Hey everybody,
So, I have a gweike (cheapish but not the cheapest chinese) 44x36 co2 laser that has been doing weird stuff lately and finally became unusable. It was getting weaker and weaker last fall, so I assumed that the tube was starting to give up because it is like 5-6 years old and sees a decent amount of use cutting open cell foam and engraving aluminum parts.
So, I replaced the 80W reci tube with a 100w tube that had also come with the laser but had never been used. The laser seemed to be quite a bit weaker after the tube swap, so I assumed that the power supply was not big enough to drive the bigger tube.
So, I got a 100/120w power supply from Cloudray that also came with a new power meter. After installing that the laser wanted to start at 10mw for several seconds before going up to 26-28, where I expected it to be. I also noticed because of this new meter that the control voltage was many times as low as 1 volt or so, so after doing some digging, I found that this machine just had a cell phone charger style 5v supply, so I ordered a more robust 5v supply in its own metal enclosure (chinadustrial)and swapped it in. It still reads low, but now is more like 3-4v instead of 1 or 2. It ran this way for several weeks, never operating as well as it used to with the 80w tube back before any of these issues, but still somewhat ok.

This past weekend it has started latching the laser on, where as soon as the laser fires, it doesn't turn off. If you are engraving, the power goes up and down between a higher and lower power, but it always has a base amount of output that doesn't stop even if you quit a program. The only way to stop the laser output is by restarting the machine. This will even happen by just pressing the laser fire button momentarily, and it will stick on at about 50-60% power and not shut off until you restart the machine.
This machine has a Leetro mpc6525 in it, and it has historically got mad every 6 months or so and needs the firmware re-flashed to it. (It would cut for a couple inches then freeze, in the past). I have tried to reflash it now but it doesn't fix this problem. Do you think that this issue might be the controller, or do we think it has to be a shorted wire somewhere? While the output has been stuck on, I have dug around in the cabinet, wiggling wires and tapping on power supplies and things and have not been able to get it to change what it is doing.

Thanks for any insight!

I would suggest checking the component that turns the laser on. I've had relays in PLCs get damaged and they will flutter on or sometimes melt fully on.

I don't know much about CO2 lasers but I assume they are using voltage input to increase or decrease power of the laser? if so then there must be an electronic component that is doing that, I would suspect it is damaged.

I've read that glass CO2 laser tubes age even when stored on the shelf, presumably due to changes in the gas composition, so it could be that even your new laser tube has aged past the point of usefulness.