When I engrave on pine that is stained I usually get a nice dark burn but I’ve recently tried cutting 3mm ply so changed the settings, I’ve now reverted to engraving again and when I do it’s engraving but not leaving a dark engraving instead it’s a really light colour.
Hi Duane,
Just a few questions 
When you were cutting the ply did you also change focus ? (focal length to most intense part of beam ?)
Is the stain the same chemical make up as the previous stain ? (many people prepare there wood in different ways for the result they want at the end. A mix of physics and chemistry 
Does the laser still cut a known material as it did previously ? ( power drop ?)
Hi, thanks for you reply,
I did try and change the focus but i didn’t really see any change when turning the end of the laser, I also changed the height, but did adjust that back, I’m using the same material and finish as when I did with the desired results, I don’t understand it, its do frustrating
And will it cut material like it did before ?
Not seeing any change in the focus is unusual. What difference in spot size was normal before
If it’s not focusing the burn, engraving will certainly be different.
Is this a diode laser ? I presume so.
Con you safely move a piece of material under the beam to monitor the been width and try the focus again.
Can you send images ?
Please check your power and speed settings one more time, but make a test piece slow and powerful just to be sure the laser doesn’t have an issue. Nothing lasts for ever … Sadly
Hi, i haven’t used it to cut, just engraving, the power setting for the frame was at 2.5 power and it was burning like it was at full power
From what, to what? You need to share more detail in posting so we know what you actually have set, and any changes you made from a working system, so we can help you get back or help determine if your issues are more than a software / firmware setting. 
Perhaps the smoke from engaving the wood made the lens of the diode laser dirty?