The Header is leaving grain on the head
Speed up the stripping rotor also check fingers for wear
The Header is tearing the complete head off
Slow down the stripping rotor
There is excessive Header loss
Slow the rotor speed and increase ground speed
The auger is plugging
Check there is at least 3/4” clearance under the auger
The combine is not feeding smoothly
See if the adaptor plate can be adjusted to reduce the dead area between the feeder chain and auger
Lower heads are being missed
Lower the Header and raise the crop deflector
Grain can be seen shooting out from underneath the front of the crop deflector
Lower the Header and/or the crop deflector