Yup, I also noticed the increased resistance when the breech block engages the trigger bar.
I bought the "original" ejector here, from Poland:
http://www.stg44.eu/wpis.php?jid=3&katid=7&postid=361
You have to request a part and pay via Paypal. The part fit well, needed only a gentle tap from a rubber hammer to seat the round tab. I needed a machinist buddy's help to get the Interarms strawed and SARCO ejectors to fit.
I also have two plum ejectors I bought from Legacy. I'm saving those for when I'm sure the ejector issue is sorted, as I think plum is period-correct for my 1939 Luger. At least that's what was on the gun when I bought it.