If you aren't a full-timer, or if you are but don't use a particular vent much, the lid can virtually glue itself down to the base after long disuse. The seal up there is such that the lid sticks to it. The company began sourcing their seal material differently in order to rectify the problem, but I've found that even with a new seal and following their cleaning and seal treatment instructions, the lid can still stick down. When it does, the lift motor is powerful enough that it can strip out the gears of the lift mechanism, and this seems to be the most common problem with the fans.
I've gone to being very careful, especially after long storage or extensive weather changes, when opening a vent. If the lid doesn't open right away and easily, I immediately turn the unit off, go topside, and gently pry until the lid just pops loose of its seal. You can do this from the inside if you remove the screen, but I usually go topside anyway so I can clean the seal and/or use 303 protectant on it which supposedly helps release in future use.
Gear-stripping may not be the Ames' problem in this instance, but it is a common-enough one that some of the Club's newest owners may not be aware of it until damage has been done. Obviously, Fantastic Vent no longer is as free with their "warranty" as a few years ago, as many of us got repair parts free from the company, even for older fans. Just watch when you turn a unit on, that the lid actually opens after a few seconds; if it doesn't, continued motor operation may strip the gears, effectively incapacitating the fan.
-Joel
