There is a baffle plate which helps mix fire and air in the burner box. The fire comes from the burner and the main air comes from the top of the burner box. These mix together at the end of the baffle plate and then turn into the dryer cylinder. The baffle helps mix heat (fire) and main air before entering the cylinder. It also keeps the flame tips from entering the dryer.
The drawing shows the baffle design.
Some baffles have cracked at the bolts and fallen down in the burner box. This creates many problems and usually results in damaged burner box sheet metal due to the intense heat.
The root cause is usually low combustion air and a long flame. The flame overheats the bolts and the sheet metal and causes failures in both.
Erratic temps on the inlet along with scorching on the outer paint is evidence of a problem.
You can reattach the baffle by welding as opposed to bolts. The bolts are nearly impossible to refit since the box is a box in a box with insulation between the two. So welding is preferable. If badly damaged a new burner box may be needed.
