So, I was about to get the 740tt ready for wheat today. I was looking up the rock trap and IIRC, at about 700 engine hours, the APS "caps" are getting rounded, but not on the side of the APS, only the middle ones. I do not believe the returns are the primary cause of the cap wear, as it should do a decent job of spreading the material by the return auger design.
It appears I need to change something to make the header feed more evenly. I have noticed much more impeller wear in the middle as compared to the sides, as well as build-up of material above the impeller. On the other hand, at times I do a "power shut-down" and the chaffer load is spread very evenly side to side, a nice benefit to the Claas design IMO.
I guess I have a few options to modify the 40' FD70 to feed more evenly.
add more fingers to the side of the auger
remove some of the middle fingers
cut a few inches off the flighting in the middle, or cut it down to the tube
a combination of the above options
This is an issue a rotor machine really wouldn't be dealing with. Having said that, this should be fixable and doing so at the header will only help the combine work even better.