Turn off the Flash Head and disconnect the power cord from the power supply. Wait at least 30 minutes to have cooled the lamp and adjusting the flash tube.
Remove the light shaper / softbox and then adjusting the lamp. Do not touch the flash tube and adjusting lamp with bare Fingers, but always use a clean, dry cloth or cotton gloves.
Now remove the wire that the Flash tube spans and pull the flash tube gently from the Base. Now remove the two small screws on the socket connector and remove the flash tube. Insert the new flash tube as far as it goes into the socket connector and tighten the screws again. Press the new tube and then gently stretch into the base and the wire spring back to the tube.