From WT by Walkthrough by MaGtRo and NKuderna
Turn the dial with the T in the hand a couple of revolutions, then stop and with the R in the hand turn the dial to 12 clockwise, stop. With L in the hand turn the dial past the 5 counterclockwise, once then stop the 2nd time you reach 5. With the R in the hand turn the dial to 20 clockwise. A click will be heard if it opens.
Maybe it's that first sentence above that makes the difference(?)