Today I cleaned the air nozzle and lens. Eventually replaced the lens.
After cleaning I noticed that the laser output was not good anymore.
I removed the air nozzle and run some tests. The output was great!!
Cut 3.6mm wood in 3 runs witch 1000mm/s and 75%.
BUT with the air nozzle, the wood is not cut after even 5 runs.
For me it seems the airnozzle is blocking the laser output.
Any ideas how to fix this, maybe some similar problems?
I too was having a problem with that. Come to find out the beam was hitting inside the air nozzle. I did a realignment on mirror #3 and it fixed it. Hope this helps. Have a wonderful day
do you maybe have a link to an image of where I can find mirror 3
No mirrors in the Sculpfun S30, diode laser.
Worked until you took it apart, right? Searched for a Youtube video on how to clean the lens for the Sculpfun laser units. The video I found is very explicit, so follow the instructions exactly and you should be good to go.
Nice device, but that is probably not a diode laser like the sculpfun is
Probably Yes 
I removed the air nozzle, with that, the lens shell (lens holder) came off.
And it was really tightened in the air nozzle. It’s a delicated brass part.
I had to remove it (with a little force) but I dented it. Not sure if that is causing all the issues.
But running without the air nozzle works perfectly. My guess is, that the air nozzle is partly blocking the laser beam. Maybe it’s not straight/perpendicular anymore…not idea
I will try to widen the hole in the air nozzle.
Also searching for a new lens shell, no luck with that yet
You can get any replacement parts directly at Sculpfun, you can search the shop (the search function is not the best, try clicking through the categories) or contact them directly. They have great support.
If the nozzle is blocking the beam can be tested with the wall test, as described here:
Once done, there’s no easy way back.
Fix or replace the damaged lens holder. It appears the air assist nozzle is located by a single grub screw, so any deformation of the lens cover holder will very likely affect nozzle alignment.