(Gweike chinese laser engraver)

Here is the problem:
First, we sometimes had problems with missing laser beam. The beam would usually reappear after the machine restart.
We suspected the magnetic switch of the cover, checked the lense and mirrors, but everything turned to be ok.
In moment of despair, we found some of schematics here on the forum and short-circuited the pins 3 and 4 on the laser PSU. But the solution was short-lived, and we removed the jumper-wire, since we didn't solve anything with it.

Right now the laser is working with cutting, but not engraving, no matter what power we set. We tried bitmap and vector engraving, with no avail.


Anyone help?!