I noticed that the correction of the PSTAB at WE were oscillating quite a lot since Tuesday. This is symptomatic of a lack of power reaching the ALS elec box. As a consequence, sometimes the 2W amplifier was not seeded with enough power and its internal securtiy was switching it off (plot 1) 
We know that the fibers are quite sensitive, for what concern the power reaching the elec box. We suspected that the problem was coming from some displacement of the fiber during the acivities at WE on Tuesday.
I went there and by rearranging the fiber I managed to get back the corrections to the level close to what they were (lower than 2V, see plot 2)

I took advantage of being there to check the temperature set point of the oven of the PPLN crystal used to convert the IR in green. I slightly changed the setpoint and checked the conversion efficiency: GREEN / IR^2. 
The setpoint was looking good but at some point, while doing the tests the conversion efficiency suddently increased (see plot 3). This looks too fast to be due to a temperature change in the oven (less than 1s). It is not explained and quite strange. It happened two more times in the following hour (plot 4). 
We will monitor the behavior in the coming days and investigate the phenomena.