Weck's website and read this:
"Jar after cooling down
A vacuum now prevails in the jar. The normal pressure of the surrounding air outside the jar presses the lid down on the jar, thus firmly sealing it. The spring clamps required during the canning process are now unnecessary and should definitely be removed after the jars have cooled down."
So, the clips should "definitely be removed after the jars have cooled down".
That's interesting. I left the clips on. I wonder why they need to be removed? The website goes on to say:
"Why is it absolutely necessary to remove the spring clamps after the processed jars have cooled down?
After processing, the spring action of the clamps is replaced by the natural force exerted on the vacuum inside the jar from the pressure of the air outside the jar. If you were to leave the spring clamps on the jar, you would not, by trying to lift off the lid, be able to test whether the jar was properly processed and sealed or not. This simple, but extremely important seal-test ( the "lid-lifting" test) cannot be performed when using jars with a thread type, a wire-bail type of closure or any other mechanical sealing devices."
I'm pretty sure that I read their website when I first purchased the jars. I don't remember seeing any of this information. Maybe it's been recently added? Or maybe I just missed it.
Later today, I removed all of the clips and checked the jars. Fortunately, I only lost 4 jars of cherries and none of the more recently canned beans or apple pie filling.
Note to self (and other Weck users!): Remove the clips when jars are cool and check the seals.