I ended up breaking the clip by trying to pry apart the two sections adjacent to the "tab" in the middle.

So, in the future, I take it that you are supposed to squeeze the clip in order for it to open?

In any casy, R&R'd the Alda line and noticed a slight improvement in acceleration. I haven't yet placed any sort of clip where the line goes into the vacumm thing - will get a clamp or something tonight. In the meantime, I assume there isn't any risk of the line being disconnected?