I of course figured it out on day one, and will smile smugly on all of you from my lofty pinnacle when the answer is published.
No, I haven't a clue either, despite having a go each time it comes up.
I did wonder whether the locking system could refer to locks on a canal, so I thought inefficient locking system could be LEAKS (which could be a pun on LEEKS) for the second word