I went through 3 machines (both Gaggia and Saeco--both have the same Rapid Steam system
), hours of searching the Internet, and phone
conversations with support(?) staff before I came up with what seems to be good options for both fixing the problem and then preventing it from being a problem again.
The Fix. Fixing the problem works better with two people, so I will refer to person 1 (P1) and person 2 (P2). To fix the problem: 1) P1 uses either a turkey baster or the small plastic (and leaky) pump packaged with the machine; 2) while the readout says "ventilate", P2 pushes the hot water button, then turns the machine off and removes the water tank; 3) P1 fills the plastic pump (or baster) with water and inserts it into the water intake valve (as best as you can, it doesn't fit perfectly); 4) P2 then turns the machine on and opens the steam wand while P1 pushes water into the intake using the plastic pump or baster; 5) as soon as P1 is finished, P2 turns off the steam valve. Repeat steps 3) through 5) until the machine has accepted 4-5 good pumps of water. If you get the "fill watertank" message, you must begin the entire process over again (if you get the "fill watertank" message every time, just keep following the process until you get the machine to accept 4-5 good pumps of water); 6) turn the machine off and reseat the water tank. 7) Turn the machine on, press the hot water button, and open the steam valve. It may take a minute, but you should finally get water. Run it until it becomes a steady stream, and then some more...about 8 ounces worth. I have found that this process doesn't always work if the machine is hot. When it's hot, it sometimes won't accept any water into the intake valve.
Prevention. To prevent the problem, I have been successful (so far) by: 1) after steaming milk, I push the hot water button and run hot water through the wand until it is a steady stream, and then about 4 oz more. 2) I always steam the milk first, then run hot water through the wand, and then make the espresso. 2) I always run water through the wand after making coffee.
This seems like a lot of steps, but it really doesn't take that long once it's part of your routine. I've been successful with this process for the last several day and before that, I was getting the ventilate message every time I tried to steam milk. I'm hoping it continues to work! It's really a shame that the technical staff have not come up with a better solution or, at the least, addressed the problems people are currently experiencing. When I called Saeco, they told me they didn't know why it as happening!