It looks like it’s complete from your pics. If you have all three of your jars and the main basket that attaches to the spindle then you wouldn’t be missing anything. I actually shouldn’t have called the black cylinder the heater but rather the dryer. The heating element is down inside the dryer. You don’t heat any of the solutions. You just put the head down into the dryer and spin the basket to dry the parts when finished cleaning and rinsing. Your machine has a stop on it so that you can’t lower the head down too far into the dryer. I think the spacers that you are referring to are the agitators that fit down inside the jars. If they are then they have fins on them and fit snug into the jars. You would push them to the bottom of the jars. They will offer some resistance to the solution and keep the liquid from swirling around in the same direction as the spinning basket. If they are loose in the jars then they are probably something else that’s not ringing a bell for me. If they are loose please put a pic of them up here when you have a chance.
As always keep having fun Steve and ask more questions if you have any!