IF its only a minor adjustment you need to make, take a look and see if there is a knot up near the top of the handle. In some bats, they tuck a bit of loose twine back into the main binding. While not seeming like much, if you are able to pull out the part thats tucked in (or used to tie a knot), you MAY notice a thinner feel. I've used the bottom bit of the corckscrew on my swiss army knife to do this and it works with a little bit of effort.
Its a long shot, but may save you some trouble.