A patient's arm is passively raised by the examiner and remains held in that raised position for over a minute, felt as a smooth, even resistance throughout the movement, until the examiner repositions it again. Before revealing the answer: is this Mitmachen?

No, this is more consistent with waxy flexibility than with Mitmachen. The defining feature of Mitmachen is that the limb returns to its resting position once released; here, the arm instead remains actively held in the new position for an extended period, with the smooth, wax-like resistance characteristic of waxy flexibility rather than the loose, unresisted movement of ordinary cooperation.