We have ran 1440's 1460's 1660's and now our 2388's in edible beans. I will guarantee you that the smaller rotor will do a better job and more gentle on the beans. We have run both standard and specialty rotors I dont see where your need for another rotor would be nesecarry. I havent harvested beans with the smaller rotor since 97. Your best bet is to set the combine up by the books setting and from there play with the rotor speed and concave opening trying to slow it down and open it up as much as possible. Edible beans are tricky but with your machine you should have no problems running 1_2 to 1% total tare. A petersen sieve will go a long way for you on the sample also. We have a company here who made us perforated screens for our dummy heads wich makes a world of difference on the amount of dirt your machine takes in.... Good luck to you
