Analysis of movement loosening

The meter sometimes has abnormal thermal resistance tapping too large displacement, the pointer is off zero or the pointer runs irregularly, etc. It was discovered that the movement was loosened when the meter was repaired. Officially, the "movement looseness" caused the abnormal displacement of the pointer when tapping the case. It is precisely because the "movement looseness" also caused the pointer to move away from zero, or because the "movement looseness" stainless steel pressure gauge would Cause the pointer to appear irregular operation phenomenon. What is the reason for the pressure gauge to loosen the movement?
      1. For the pressure gauge of the formal movement, the reason for the loosening of the movement is that the fixing screw of the movement is not tightened after the adjustment of the pressure gauge is completed, so that during the operation of the instrument, due to the repeated tension of the connecting rod , The movement will be loosened. Second, the defect of the movement itself may cause the screws to fix the upper and lower plates on the movement not to be tightened, causing the stainless steel pressure gauge or the lower plate of the upper and lower plates of the movement to loosen during the operation of the instrument. If the field vibration of the instrument is large, the time is long, and the upper plate of the movement may even be shaken off.
      2. For the pressure gauge of the reverse-mounted movement, the reason for the loosening of the movement is that the movement is not tight when the movement is connected to the joint, but it is loose during use, and the other is that the movement of the movement is connected to the movement. The outer diameter is too small, or the rivet hole is slightly larger, causing the movement of the instrument to loosen during use.
      3. Another is that the user of the meter disassembled the movement surface out of "curiosity" or "good intentions to repair" the thermal resistance, but failed to install it properly.