I have a Peak 2 and don’t feel any ‘thunk’ at the end of the string.
And I do have a few thinkers in my large herd of yoyos, lol.
If the gap is possibly the problem; maybe try a thicker string to offset the gap?
…I use Kitty 1.5 or kitty thin; a lot. Usually I change over to Kitty Fat when a yoyo seems to be in thunk mode 
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…Also, if your bearing is super clean; combined with thinner string; the Yoyo will have more tendency to fall down the string.
If you figure it out; please post an update because you sure got me wondering🤔