RIGOL  Chapter 1 Disassemble and Assemble 
1-10  MSO4000/DS4000 Service Guide 
  It is recommended that you use a lever-like tool to pry out the knob when 
disassembling the knob and place a soft pad at the force bearing point to 
avoid damaging the key film and knob. 
  Removing the key film would reduce the stickiness of the glue and repeated 
use of the film would resul
t in unreliable paste. Therefore, if you only want to 
view the main board, you only need to disassemble the rear metal cover and 
you are not recommended to disassemble the front panel.