Help My seismic sink leaks...

I have an older Townshend CD seismic sink (no lights), that seems to have lost its ability to hold air. There's got to be a leak somewhere. I'm wondering if anybody has had any experience opening up one of these units. I removed one of the legs thinking that would be a way to start, but I don't think that's the route to go: there are no screws involved, the leg (made of rubber) just pops out of its hole. The only other way seems to be to unloosen the nut holding the air intake valve and go from there, but I'm worried about damaging the thing, or going in a direction I can't reverse.

Has anyone had experience with these? Also, there is a warning about chemicals inside that could damage the unit. Anybody know anything about this? Is there some kind of 'trick' to opening these devices?

Thanks.

Nick