LEAK RATE IS: 3.1 mmHg/min
First, while in STERILIZE look for any steam leaks.
S1 valve is a common cause.
One of the Poppet check valves back on the heat exchanger, I can't rember which one off the top of my head. Door gasket, Last I would rebuild the entire exhaust manufold to include the check valve.
Is it failing the DART (Bowie D**k) test? Does the temp rise as the vacuum level rises? Need to try and determine if the leak is air or steam. What is the max vacuum you are achieving?
Mostly repeating Jeff's good advice with a few extra details, that's not a terrible leak so seeing it lose steam under pressure will probably take a dental mirror. Look for fog on the mirror as you probe around components and fittings that connect to the chamber, don't forget the chamber float switch and pressure transducer.
1- S1 valve - Just rebuild it and get it off the list. This is the weakest component between the chamber and atmosphere. Remember, the brass ring goes in the valve body first then the o-ring.
2- S3 valve / Exhaust manifold - Rebuild and check the valve seat for pits or cuts. Also check carefully the piping and union between the manifold and the chamber as well as the probe fitting.
3- Door gasket - Replace and clean end ring channel. Look at the inside of the door from behind underneath and look for debris around the gasket sealing area. Especially load stickers!
4- CK2 - Between waste funnel and heat exchanger. Disconnect flare fitting, turn the fitting/check valve to the side a bit and check for suction with S7 open to diagnose. This mostly causes poor vacuum / wet packs not chamber leaks, but worth checking, same for the heat exchanger itself leaking between sides internally or leaking from the hot side externally.
After that, it really becomes a goose chase. Good luck!