This afternoon I have been contacted because the ITF was not locking. The problem was coming from the SSFS which was behaving badly, there were plenty of oscillations and saturations and it was unlocking repeatedly. 

Alain checked that there was no problem coming from the SSFS itself.

As the gain was very high in general (around 5 V) I lowered the gain significantly at every step of the lock acqusition and the glitches disappeared. However, this seems surprising knowing that the IMC transmitted power has decreased by almost 1 Watt during the WE.

I also tuned slightly the working point of the PR TX on LN1-LN3 after the work of Ettore.

The ITF seems more stable now.