1: Never had this error, though it has been wobbly once or twice, but still ran. It just leaked some. The one I use just flushes automatically at the end of every run while its running the dryer. Drain I believe just drains whatever is being held in the tank and shouldn't have to be done first.
2: Is it just chipped for the 4 step version possibly and not the 7? You may have to get a new one for that.