Elenna and I checked the FC detuning by taking it slowly from nominal -26 to -50, where we could clearly see low freq DARM was worse, and then stepping to -15 (any lower unlocked the FC in 85886) using ezcastep H1:IOP-LSC0_RLF_FREQ_OFS -s 30 '+1,35', see attached plot. The best de-tuning is close to where we already are, leaving it at -27.