1. Remove the mounting block (see "Removal and installation the mounting block").
2. Remove the eight screws securing the bottom cover.

3. Use a screwdriver to pry up and open the bottom cover of the unit.

4. Check the condition of the conductive tracks and the quality of soldering. Eliminate possible defects. If this cannot be done, replace the unit.

5. Install the mounting block in the reverse order of removal.
