My new corny keg had a really strong soda odor when I got it a few weeks ago. I soaked it in PBW and everything smelled fine. I put a finished Kolsch brew in it two weeks ago today and it's been carbing up since. I pulled a pint today to see how it's coming along and noticed that it has picked up a faint fruit punch scent, like the odor I thought I had gotten rid of. Not good.
I thought that my LHBS guy had replaced the gaskets, but apparently not. The lid o-ring still has a strong soda odor and I realize that I'll need to replace it and all of the other gaskets, but that doesn't help with my (potentially) ruined batch. Upon detecting the "contamination" I immediately hooked up my picnic tap to the spigot on my bottling bucket and transferred the beer into a "neutral" environment to at least prevent it from getting worse. I tasted it again and the odor/taste is definitely in the beer itself, not just the keg.
So, short of learning to like a sweet, fruit-punch flavored Kolsch, does anyone have any tips for getting rid of an odor like that?