Thank you, Cooldmax, for taking the time to take the pictures and post a response. What you show is exactly what I have. I see now that the venting takes place through the two formed tubes on the underside and around the circumference of the circular piece on the top side. I was incorrectly picturing the venting occurring though a small hole in the center which appeared to be covered by a 7/16 diameter cap. Still not obvious why the top center projection is there. Perhaps a remnent of a past design or a process requirement.
Thanks again,
Bill