I am not sure how to pull the retainer, but last time I cleaned the coupler I did noticed that that plastic ball in the coupler had a very strong minty smell. It did not smell "skunky" but very "fresh and minty". Although fresh and minty can be good, it is not an attribute that I look for in my beer
In hopes to resolve the issue, I ordered a new coupler from micromatic.com last night.
Thank you all for your comments, they were very helpful.
Regards,
Jon