The 20 series are not bad combines, but if you have quite a bit of wheat I would stay with the axial flow and not be fighting walkers. The main thing on them Deere ist grease. If they have been greased well you should be save. They wear some in the feederhouse area, threshing and clean grain section. You just have to look at them closely. But if they didn't get greased, it's like everything else. You start replacing the variable cylinder drive, bearings and countershafts and rack up a $15,000 parts bill easily.