I found that TRY level degraded and the beam shape seen with CCD camera at AS port was splitted when the beam spot on ETMY was not close to the center. This was because dither started not working well. I suspect so because in such a case TRY level went up when I did iteration with TT1 and TT2 after freezing dither. Splitted beam shape indicates that incident light did not match well with the cavity mode.
TRY level for each point was this:
[[ 0.6573 0.8301 0.8983 0.8684 0.6773 ]
[ 0.7555 0.8904 0.9394 0.8521 0.6779 ]
[ 0.6844 0.8438 0.9318 0.8834 0.6593 ]
[ 0.7429 0.8688 0.9254 0.8427 0.6474 ]
[ 0.7034 0.8447 0.8834 0.8147 0.6966 ]]
In the worst case, TRY level was 70 % of the maximum level. Assuming that this degrade was totally due to the mode mismatch, this corresponds to ~50 urad difference between the angle of incident light and resonant lighe in the arm (see elog 11819).