That's what Steve said. I asked him "Where are the air vents?" He said "I have no idea."
But that is just what it seems like...because when the tub releases, it's like it pulls a suction on it...it just sucks down quick!
The air vents go up through the roof. You can find them there and snake down them, you'd be pushing whatever clog right into the drain. All your fans vent their too, but you can tell which ones those are.
Didn't you say it's always been kindof slow?