I managed to recover the "good" error signal of GRMC. It turns out that it actually did have something to do with the optical part, or rather the SHG output oscillation. I didn't turn down the gain on the SHG quite enough, so residual power oscillation made its way to the green error signal port (GRMC REFL RF), visible on the GRMC EPS2 OUT when the MZ is not locked to stabilize power. After adjusting appropriately, the GRMC error signal became the usual PDH with about 1 Vpk. I locked GRMC/MZ then checked the output power with the power meter - it sits fairly stably at 26.3 mW when the MZ servo is set to 4.2 offset, which is consistent with our usual work. The GRMC output power also had some oscillation at the nominal good gain - I had to reduce it from 3 to 1.4. While I am not certain yet if this is a byproduct, the GRMC output power is extremely sensitive to acoustic noise. Tapping foot makes a wave in the output. I don't entirely know if it is SHG, MZ, phase shifter or GRMC. Maybe can try also tweaking MZ gain and see if that fixes it or makes other things worse.

Initially I couldn't see error signal for IRMC, but the cable was disconnected. However, the error signal is not normal. It looks like a low detuning/transmission signal for PDH rather than the more familiar high detuning reflective form. I checked that it goes to zero when blocking IRMC REFL so it wasn't a misconnection to a transmission PD. I tried connecting some longer cables to change the demodulation phase but it doesn't change much. Then I found that the IRMC DEMOD LO signal was changed from DDS1 DAC1 (has a splitter which also goes to SHG DEMOD) to DDS2 DAC0, which right now is redundant (previously used for GRMC EOM which was removed from the locking scheme). This has a good intention since we don't have to bother with fudging the cable length or using an IQ demodulator. I checked the LO strength and DDS2 DAC0 is quite weak at -9.7 dBm. I checked the splitter channel DDS1 DAC1 (4.5 dBm) and tried using it as IRMC DEMOD LO but the error signal was still quite bad. IRMC will also not lock. 

I don't know whether or not to be concerned about DDS2 signal strength. GRMC DEMOD and the main 88 MHz EOM all come from weak signal ports but are RF amplified to about 0-5 dBm level. There are some RF amplifier ports +14 dBm that are unused, labelled "NO USE". I didn't check if that means they were broken or just unused. Next time.