http://www.kiya1.de/beyond/act1screens/Act1drillever0.jpgTherethere, dry your tears, Swordfish - flip these levers according to the pic link and then you will see the exit door open. The key this guard dropped, merely opens a small lever room - did you do that? And this opens a gap in the east with the levers.
There is no cut scene indicating, the door to the exit is open, so either split your chars (leaving out the 5th lever then) - or place a summoning doll near the exit door and switch after each lever to check from when on the door is open. <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />