I tested everything. the fuser is ok and i used brand new cartriges. so the drum and relsted thigs are ok. the funny thing is that when i use first tray the printout is ok and only the paper in the bottom tray get these spots. thats why I think the fuser is ok
When you hold down the right SHIFT key for 8 seconds, you should hear a tone, and the “Filter Keys” icon will appear in the system tray. Just then, you'll find that the keyboard is locked, and you can't type anything.