@Julio-Souza I don't fully understand what you mean? I connected everything as usual but the laser did not react to any PWM. I also disconnected the PWM plug entirely (I saw that somewhere on the forum) but nothing happened.
This morning I started measuring the board with a voltmeter and the PWM port seems to have a direct connection to ground. Is this normal or is this a sign of some short circuit on the board?
You can add a pull down resistor to fix the laser pulsing issue, it’s been discussed many times. The problem is a poor design of the laser driver, this simple update makes it much safer.
I haven’t experienced the bearing / wheel issue you describe with either the older white POM wheels or the newer black version. Possibly they are too tight? If you have a 3D printer you can make an adjuster which may help.
I'm not sure what you mean about executing multiple G-codes at one time, do you mean if you send one and then send another? That is OK, it's only when you disconnect the machine and then reconnect that the pulse happens during boot up.