/21All firebrick and duraboard baffles must be properly in place for correct burning operation. Have anydamaged firebricks replaced. Check the firebricks annually for damage and replace if they are broken ordamaged. See Figure 3.3 for the firebrick layout. Install the side & back firebricks first, and then thebottom firebricks.Figure 4.2 – Firebrick layout4.5 Secondary Air Tube Replacement(see Figure 4.3)1. Remove cotter pin at LH end of tube.2. Slide tube to right and lower tube end below LH plenum.3. Slide tube to left to remove.4. Reassemble in reverse order using a new cotter pin. The cotter pin is a hammerlock style andlocks into place by hitting the head sharply with a hammer.5. Note that any tube can be replaced without disturbing the baffle.