Iceanubis, have you tried tightening the screws on the case? That was a problem with my PC after I opened it up; a whole shitload of tweaking with the screw tightness fixed it.
Uh not going to lie, I didn't check this topic after my last post until now. Anyways, each bladder has 2 holes; one for in and one for out, right? Well I figured that if you used something like 2 4-way tubing connectors, you could link all the inputs and all the outputs to one 4-way connector each, and then use the remaining opening in the connector to connect the now linked bladders to the pump and output area.
You know, I haven't tried that. However, I will try to mess with the screws and see if it makes a difference. If not, I have a big, complicated mess to deal with since I would intend to either mod the wheel thing AssassinNF was talking about or make my own lever system. I'll give you an update.