you have potted the end caps? http://wiki.openrov.com/index.php/Potting_the_wire_pass_throughs_in_the_end_caps
have you installed the syringe when gluing the endcaps?
have you mounted the o-rings?
if yes, its a matter of following the steps a the bottom of this page(more or less the same thats going to be in step.15) http://wiki.openrov.com/index.php/Assembling_and_Gluing_the_end_caps
i would check the module for leaks without the e-chassis installed. its alot of money and work to replace for a small leak.
the servo is not powerful enough to rotate the e-chassis at the moment. a new e-chassis is in design to rectify this problem.
as of now you should power the electronics with the servo attached, but not connected to the end-cap. when the servo starts up, it need to rotate freely so it can move to the zero point of movement.