On the 2188, check if the bushings on the shaker have been replaced recently. Also you will want to take off the half moon cover above the feeder house and inspect the transition cone and AFX fighting for wear. Wear on the cone is about 1500 to replace with aftermarket and ALOT of work. Check all of the auger fighting everywhere, and general condition of belts, pulleys and chains. Run the separator and check for weird noises and excess vibration, so shaking back and forth from the sieve system is normal but the rotor should be balanced well enough that it doesn't vibrate much. On the torque sensing rotor drive pulley you should replace the spring right away with the heavy duty unit ($43), be careful not to take your leg off in the process
You will like the capacity in fall crops, from the gleaner guys I have talked to you will gain capacity in beans and milo. Wheat will probably be a wash. If you find you want more HP you can turn up the pump, or do like I did and send your injectors off for extrude honing. The nice thing about the honing is you are actually feeding less fuel per HP, we saw about a 10% decrease per hour with a 20% increase in capacity, all for $300. That's all I can think of, you will like the cab better too.
