Having just dealt with the same problem in WI corn with a different make of combine, here are my general corn shelling suggestions...
1. make sure feeder, cylinder bars, concaves, clean grain auger, and elevator are in good usable shape; and make sure engine speed is correct.
2. set combine as your OM suggests.
3. set combine ground speed to feed combine evenly w/o overloading. *
4. adjust cylinder speed to minimize damage. **
5. if adjusting cylinder speed doesn't eliminate damage, part of the concave must be fully opened, reset to OM recommended cylinder speed, and repeat 4.
6. adjust concave clearance to produce fully shelled cobs out the back of the machine. ***
* too little ground speed and the corn will sit in the cylinder grinding away. the cylinder can handle A LOT of cobs in easily shelled corn, you will likely overload something else behind the cylinder before you have too much corn in the cylinder.
** generally, cylinder speed is the key to reducing damage. however, if you need to maintain a slower ground speed, a faster cylinder speed may actually be needed to maintain good flow of grain through the cylinder, preventing damage.
*** reducing cylinder speed may result in more kernels left on the cob behind the machine. close the concave by about 1/8" at a time until complete shelling occurs.