I have used these cleaners for quite a while, after admiring them from afar. $ 1600 is a costly price for a cleaner that you can't really justify, but this is what you get for something sold by a pyramid of sales people, each of whom must get his cut. I lucked out in a similar way that you did, and was able to get one being auctioned by the finance company holding the paper on contracts that had gone into default.

The clear plastic bottom has a small post in the middle, that indicates the fill line. Fill to the top of the post, unless you are going to vacuum up a spill off the floor. If this post is broken, fill to about an inch and a half.

Rainbow feels that you should take great pains to pour the dirty water out over the side of the bottom water container, as opposed to out the same hole to which the vacuum hose is connected. They feel that pouring the dirty water our the input "spout" will introduce dirt and grit into the area where the hose seats. Over time this grit will cause excessive wear, and the cleaner will lose vacuum or pick up power. Note that at the top of the cleaner "wand" there is a sliding cover that occludes several holes drilled in the top of this wand, allowing you to deliberately reduce the vacuum for delicate tasks.

There are two different sizes of bottom units for these cleaners, and they can be obtained from most local vacuum cleaner dealers, to save money. Early models, 10 - 15 years ago - Rainbows could pick up additional water until it shorted out the motor. All of the fireworks would be in the cleaner body though. Later models simply shut the motor off if the water level in the bottom gets too high.

As far as safety goes, the water is contained in the base of the cleaner, which is connected to the wall by an insulated electric ccord, and to the pick-up head by an isulated hose, to the aluminum cleaning pipe or "wand". Any fireworks from over filling one of the older models will be contained in the body of the cleaner, and not out to the cleaner "wand" to the user. The newer models have been designed to simply shut the motor off.

I'll see if the local vacuum shop has a Rainbow User's Manual, and send it up to you.

Dave