We are able to lock the PMC on the TEM00 mode of the deflected beam.
However when we turn off the driving voltage to the AOM and back on the lock is not restored. It get stuck on some higher order mode.
There are plethora of modes present when the PZT is scanned, which makes us believe the cavity is misaligned.
To lock again on the TEM00 mode again we disconnect the loop (FP Test point 1), find a TEM00 mode using the DC output adjust and close the loop again.