Hello fellow members.

I have searched high and low on this forum for my answer before posting this, I did find some great advice on comparable threads but no definitive answers.

My issue has to do with gradual power decreases with my Shenhui 690 laser (90watt RECI tube).
Put simply, the settings I would use when I first purchased the machine in January barely mark my substrates now.
I only ever mark wood and as an example when I etch bamboo I used to do so at %26 power, 370mm/s speed, results were perfect.
Now, just 8 weeks down the track, to get a comparable result I have to run it at around %38 with the original %26 barely making a mark on the surface.

Obviously over time tubes will decrease in power and results like these would be typical, the problem is, its only been 8 weeks!

The 1 contributing factor that just may really help narrow down the possibilities is the fact that perhaps coincidentally (but probably not) I had the exact same thing happen on another Chinese laser (not Shenhui) that I used to own.

I maybe off in my potential diagnosis but I feel it has something to do with the grounding of the machine or the power that is being supplied to the machine.

I am far from any electrical expert so have steered clear of fiddling with what I dont know but understand that as the power cords have 3 prongs they should essentially be properly grounded?

There is the usual ground point on rear of machine which has good contact with one of the garages steel support beams.

The machine is in a 40+ year old garage which is why I thought initially suspected some sort of power issue to be the cause but I could be well off the ball there.

All mirrors and lens have been checked and regularly cleaned, the lens had a dark spot on it but replaced with new piece and wasn't the culprit of the poor results

Your suggestions would be greatly appreciated.

Please keep in mind im in Australia, assuming replies may come from the US please forgive any lengthy delays in replying, I appreciate any and all guidance.