Why does my machine work only one side?

Why does my machine work only one side?

To confirm the issue in detail, could you please kindly help us confirm the following information?
1. Please check the wiring of the heating tube and gear switch to ensure that the wiring is secure.
2. Please adjust the gear switch to the full heating position.
3. Please check whether the gear switch and heating tube are damaged. Wondering if you can take a short vide for us at services@callsupport.com to analysis in detail if convenient?
Everything is fine except that it does not heat up and the heating tube does not heat up. If there is no problem with the above, we would like to reissue the heating tube.