This is not the issue of the alignment but the AOM driver. The AOM driver is completerly out of order now. The attached picture is the output RF signal from the AOM driver. It should be the sinesoidal signal at 110 MHz.

So we need to replace it to new one, but actually we have another choice to skip the FSS loop and fed the MC signal to laser PZT directly. We need to discuss several possibilities.

I replaced the AOM driver by the miyoki-san's one. The "mori-coart" was put between the AOM driver and the heat sink. And also I simplified the cable configuration around the AM input of the AOM driver. The cable configuration before and after the simplification are as follows:
(old) DC power supply (banana cable) ------------ (BNC) I connector (BNC) ------------- (SMA) sma2smb conector (SMB) AOM driver AM input
(new) DAC ------- Dsub-BNC converter (BNC) ---------- (SMB) AOM driver
The channel name connecting to the AOM driver AM input is K1:PSL-AOM_AM_IN. The input voltage is set to 1.5 V.

After replacement, I found the banana cable is broken. The problem came from not the AOM driver but that cable

Anyway, the FSS loop is healthy now.