Problem with the skylight. He worked normally. Now that an attempt is made to open nothing happens. Neither the glass nor the blinds move. I can open both the glass and the blind by hand. On the reset, both the glass and the shutter close. When the shutter reaches the end, it starts to thump. The front engine does not rattle at all, but the rear is heard when closing. What to do? Can you give a closer explanation about holding the Z key when resetting? Does it stick all the time or just near the end? Does this apply to both the front and rear engines?