The nuts and bolts for the large flange are galling:
This set is shot.
These sets are pretty expensive, so I asked MDC for a free replacement… which they gave me!
Galling is pretty common with stainless on stainless. One solution is to use anti-sieze:
But this introduces goopy hydrocarbons to my clean chamber.
MDC’s recommended solution is silver plated stainless steel bolts. At $77 for a large conflat it’s very expensive… but the way to go.
Prometheus Fusion Perfection 
definitely expensive! crossing my finger is works… and congrats on the probe!