I'm sure if anyone buys a Rainbow that happens to be really dirty inside, it can be taken somewhere to be taken apart and sanitized on the inside. I know the distributor here charges 65 dollars for that, but I have never had it done. Mine doesn't need it.
Good vac is great. They have every part for Rainbow that exists I think. I bought the 14 foot non-electric hose and it's GREAT if you live in a house with vaulted ceilings. I can stand on an eight foot ladder and clean on top of cabinets, ceiling fans. It comes in very handy to get those REALLY high places that I can't get with the standard size non-electric hose.
After having owned it for several years, I think the most important things are:
1) Change water before it gets too dirty and don't fill the basin with water over the dome in the middle
2) Keep and eye on the separator and clean it with a toothbrush if it needs it
3) Don't turn the machine OFF and let it sit with water in the basin. For example: If you're in the middle of vacuuming and you stop for an hour or so to do something and you're going to finish later. Take it off the basin with water in it.
4) If you vacuum up liquids with the non-electric hose, be sure to fill the sink with some CLEAN water and suck clean water through the hose to wash it (careful to not let the water get past the top of the dome in the basin), then put the hose on the exhaust to dry it.
Seems like a lot, but it's all simple really.