The baffle is a spiral device that hangs down inside the chimney to slow the heat rise from the propane burner. It concentrates the heat on the boiler section of the cooling unit. A missing baffle will cause erratic cooling while operating on propane.
If there is a problem with the baffle it is usually caused by human error. Some people think it is a chimney cleaner and remove it. More often, when a cooling unit is replaced the person changing the cooling unit fails to transfer the baffle from the old unit to the new one. The remedy is to install it.
Sometimes the wire holding the baffle corrodes and breaks. If this happens a metal coat hanger can be formed to replace the wire. You should note that the baffle is designed to hang at a certain point in the chimney. You should copy the length of the old wire if possible. If you're not able to copy the old wire, a general rule of thumb is that the baffle should hang at about the same height as the electric element holder.
Also, if you have had a very sooty flame in the past, the baffle should be pulled and cleaned, and the chimney itself should be cleaned.