I have a special Voodoo hammer here, it might help, but it might make the lens less able to focus on its own too.
What is the chart like WITHOUT the Tc attached, just for comparison. Don't move the camera, just stick the chart up, shoot WITH the Tc, then take the Tc off and shoot again without touching anything, other than focus. See what the results are. If they remain soft at the bottom I would think there is a plane shift in the bayonets and the workshop is your only recourse, with BOTH sent in for optica matching.