Combines 1993 John Deere 9600 Combine fire investigation

We had four fires in 9600's and one in a CTS.the fires originated in the pvc tube behind the cab that shields the primary gearcase shaft from mog from the backbeater wraping on the shaft. The problem starts when the tube is not kept clean and debris fills the tube and rubs on the shaft causing heat to build and a fire.Field pea and flax dust are the most of tha problems.You can get access to the pipe from the cylinder belt side under and behind the top pulley,a 7ft long flexable blow pipe and a love for dust is all you need...lol... (PS) we cover this pipe during our Greenlight combine clinics for our JD walker customers