The X arm ASS was also fixed. So both X and Y arm ASS are now back to normal.
Now we can align the arms any time from the buttons on the C1IFO_CONFIGURE window.
The reason why the servo didn't work was that the sign of some control gains had been flipped.
This was exactly the same situation as that in the Y arm ASS (#5067).
The servos of C1ASS for the Y arm and the beam axis alignments were fixed.