I have a cx840 with around 2400 eng 1750 sep. If its been maintained you should have no worries with it. Ours is being slowly rebuilt as we find more and more things wrong with it. Machine isnt great on canola. We seem to harvest for a day and stop for two at the moment. We have a 36ft 994 Honeybee on it. Had issues with threshing barley and wheat last year. Id check final drives and the main pin in the rear axle. Our pre sieve was ready to fall apart right hand top walker bearing wasnt installed properly and wasnt getting grease. Actuator for sieve leveling was dead, would go to one side and stay there, except the header told you it was level. Sieve adjust would work and top and bottom sieve would shut on there own.