Vintage KA Performance.
I don't believe this dishwasher heats its water, so make certain your water heater is turned to 140 at least. Most dishwashers are plumbed into the hot water line under the kitchen sink, so run the hot water at the sink until it is fully hot before turning on the dishwasher (all dishwashers, not just yours).
Also, dishwasher detergents were just reformulated to remove the phosphates (specifically STPP, or Sodium Tri-Poly Phosphate). The new reformulated dishwasher detergents simply aren't cutting the mustard (literally or figuratively) so it may be a problem with your detergent, not your dishwasher. Go to The Chemistry Store .com and order a small pail of STPP / Sodium Tri-Poly Phosphate (link below). Put a teaspoon of STPP with your detergent in the detergent dispenser and see if that improves things. Depending on your water hardness, your detergent, and your water temperature, you may need to use more or less STPP, but a little experimentation will tell. A tablespoon of STPP in a top-loading washing machine can also work wonders.
See the threads in the Super Forum on dishwasher detergents.
Good luck,
Dave
PS: If you load a big pot in the lower rack, it will block spray to the upper rack. Load the bottom rack such that water can spray through it (like plates) so it can wash the top rack. The Kitchenaid 15 series is actually a fantastic performer, provided the water is hot enough, the detergent is effective, and the lower rack's contents won't block spray. One of the reasons why the KAs of this era had no upper spray arm is because they simply didn't need one. With proper loading, they are effective without one.
http://www.chemistrystore.com/product.cgi?group=88793&product=88794