We have an 08 8010 that still has a factory warranty on it till the end of this year. When cutting tough small grains I was really putting the wind to her. With high fan and rotor speeds the cleaning fan would begin to surge! The surge is anywhere from 100 to 200 rpm, you can hear it in the cab as well as see it on the monitor. If anyone has experience with this let me know, or any ideas. Thanks in advance!!