Ridiculous ergonomics pertaining to the center-north flange that was R&Rd significantly limited my ability to do a decent job on the chamber flange (predict 50/50 chance of having to revisit this "leaker").  After several hours of fighting the numerous obstacles, I finally unbolted the dial-indicator "trees" that monitor the support tube motions.  Sorry Seismic.  Unfortunately, this was mostly after the fact.