Door deadlatch sticks open

I have an exterior door with a keyhole-in-knob deadlatch. With the recent cold weather, the latch started sticking open when it gets pushed in while closing the door, so the door doesn't latch shut. I figured out that the deadlatch was sticking to the main latch, so the main latch couldn't spring back out into the door frame.
So I rubbed a pencil (a quick source of graphite) in the groove in the main latch which the deadlatch rubs against. It worked for about a week and a half, and now the problem is back.
Should I try more graphite, or a different type? Will adding WD-40 after graphite gum up the works? I'd really prefer not to replace the whole doorknob lock because of this simple problem.
Jimmy
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snipped-for-privacy@mailinator.com wrote in

The pencil lead contains clay as well as graphite, a mixed blessing for your application.
WD-40, depending on the exact version, is mostly kerosene, which lubricates for a short while, then evaporates, leaving behind who knows what.
My locksmith recommends 3-in-1 oil, but just a drop.
I recommend that you remove the entire knobset, clean it well, and reinstall it. It's amazing how often I fix something just by taking it apart and putting it back together.
--
Steve Bell
New Life Home Improvement
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Jimmy,
If taking it apart and cleaning doesn't work, you may be able to just replace the latch internals.
One of my exterior doors wouldn't close unless I turned the knob. Cleaning and lubricating didn't help, so for $10 I replaced the internals and all is fine. Look in the door knob section of your local big-box store.
dss
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