Benchracer:

Those little black thingies that hold the plastic tray over the vac lines are a flat circle with stick attached which goes into a split plug and acts like a wedge to hold it in place. They are a royal pain to get out without ripping the head off! Best way I found to remove them was with a wire cutter. Carefully use the jaws to wedge the head up to pull the plunger out of the plug. Still riped a few heads off anyway. }:-|

Good luck!