snorri point to a truss not far from harrenden.
"there is a hidden panel there, in the beam, it has a lever, all you have to do is pull it out, then spin it three quarters of a circle and then push it back in. it takes a bit of strength to do so, but i imagine you will be fine. that deactivates the mechanism, so the trap wont spring on you."
he seems very upset that you are unwilling to let him do it himself, but is resigned to letting you disarm it.