One of the most common and earliest wear points for the 4r70 is the torque converter clutch. When it starts to wear, it creates a shuddering as it engages, and the only fix at that point is replacing the torque converter. One of the changes in the formulation of MerconV was to address this, but it can still happen even with clean fluid. The ECM modulating it is actually part of the problem. With the small hole, it takes longer for that clutch to fill and engage, and when the ECM is rapidly turning that solenoid on and off, the fluid can’t flow in and out fast enough, and the clutch wears and shudders. Making this hole significantly larger will resolve this problem, especially if done before the TCC shudder has presented itself.