The correct length of the screw can be easily determined by putting the screw into the screw hole of the top section. The length is correct, if the screw projects 4 - 7 mm. The top section is anchored to the base section through the oval slots of the elevation block.
For fixing the top section, please use an accumulator screwdriver with bit PH-1 (drilling screw DIN 7505/P with Philips PH-1 head). Under slight pressure only and setting an average torque on the accumulator screwdriver, the drilling screws drive a thread into the screw base of the base section.
Dismounting:
The screw can be unscrewed and screwed in again without any problem.