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The deadlock on our front door has worked fine for 2.5 years. You could hear a "clunk" when it was turned. Now, all of a sudden, the latch slides over silently with no resistance. The major problem though is that when you try to lock it with the key from outside, it unlocks when the key is turned back for removal. The resistance, or 'weight" of the latch is simply too low. I have taken it apart twice but can't really find anything wrong with it, except it moves too easily. Help please!

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I'd have to see it, but it sounds as if the lazy tailpiece on the back of the lock cylinder has stuck in place and stopped being "lazy". If the problem started after you disassembled the setup, you may have gotten the timing wrong when you reassembled. – keshlam Jul 8 '14 at 0:25
Thanks for the answer. The problem occurred all by itself however. I don't know what the lazy tailpiece is but I assume it is the piece that should "stay behind" and not move the latch back when the key is turned back. It seems that the problem is with the latch though since it doesn't move over the way it used to. Previously, when you locked the door, the latch "semi-locked" into position, and to unlock it a little force was required, resistance which I assume would also have kept the lazy tailpiece in place. The latch now moves back and forth with almost no resistance. – Unsafe Jul 8 '14 at 13:21
Hmmm. Let me think about that. If the bolt isn't extending all the way it may not be getting into the fully deadlocked position... sounds like something is pressing back on it but without looking at the lock itself I'm having trouble thinking of what could be doing so. – keshlam Jul 8 '14 at 13:35
Thanks again. I think it is extending all the way. Previously, and on the other similar locks, when you lock, or unlock, them it feels like the latch is going over a "hump" and semi-locks in the position on each side of the "hump". It sounds a bit stupid but it is the best way I can describe it. Hence the "clunk" or "clack" sound I described earlier. Now it is almost silent and you can hardly feel that you move the latch. Maybe a piece of wood has fallen into the moving mechanism (it's like a little box) partly hindering the movement. I will check for that if I can manage to look into it. – Unsafe Jul 8 '14 at 17:39
I once again opened the lock and examined it carefully. I could find nothing wrong with it. I also "greased" it up with some graphite powder. It's not like it was but at least it doesn't unlock when I take the key out. I tried at least 20 times and it worked every time. I don't think I will leave without checking that the door really is locked though. Thank you keshlam for your input, I certainly learnt something. – Unsafe Jul 8 '14 at 20:00

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