I also bought a new 226 and several times it failed to lock back on the last round. I am going to have my firearms unit guys look at it. I will let you know what they find.
I also got the plastic guide rod. I ordered a brand new one from Steve Bedair (he sells them on a website I believe its guiderod.com, I just googled Bedair guide rod). The Bedair comes in stainless and works like a charm. Steve was excellent to deal with and emailed me right after I placed the order and when it shipped, which was the next morning. Excellent sale and a great guy to deal with.