I purchased a flow-thru humidifier a year ago. Had problems with it this year (the electronics on board would not trigger the solonoid to open) and I tried to get service from Home Depot to get a new one or order new parts. They were at a loss due to the fact that they did not carry the same product anymore.
I was informed that I should just buy a new one instead.
I found the manufacturer online and told them the issue. The manufacturer sent me a replacement in the mail within a week.