Your biggest problem that is causing your slip clutch to slip too much is the worn top auger. Your slip clutch not only has to drive the clean grain auger and elevator, it also has to drive the worn bin loader auger. The worn flighting will not push the wet corn out the tube very well, especially as the bin fills and the grain rises above the auger. This causes an overloaded condition for the slip clutch and it does the job that it was designed to do. Replace the worn bin loader auger and you will see a definite reduction in the clutch slipping.