I moved the lens just before the PMC to check the mode matching landscape. The PMC trans went up from ~6.5 to ~6.8. That's 5% with ~1 hour of work.
As per the micrometer, this took ~7-8 mm of travel. Since there's so much power left in the HOMs, we we we will have to do a proper mode scan and re-calculate the solution.
The measured transmission is now ~610 mW. The power reflected from the PMC with it unlocked is ~1400 mW.