Where's the vent?

[wolfman]

My whistling gas cap was back after a warm day ride 2 days ago.  Remove the cap, whistle goes away, cap back on, whistle comes back after 30 seconds or so.  So...I removed the cap and took it appart. It was quite rusty inside and the spring appeared to have been frozen.  Cleaned up with a Dremel moto tool, freed up the spring and "ear" plate,  greased lightly and reassembled.  Cap seems to fit better now, but I did not see anything in it I could identify obviously as a "vent".  I have not had a chance to ride the last few days, but am concerned that I may have actually managed to seal the cap better rather than open up the vent?  So did I miss it?  Where is the vent in the cap? (Worried about potential vapor/vacuum lock)

[Don Minor]

 :)Just had my cap apart today. You should have seen a small groove in the large plastic piece.At the end  of the groove there should be a very small hole. It has a check valve in it so air goes one way.Mine worked ok so I made a new gasket and reasembled.Waiting for sealant to cure before I put gas in the beast.I'm doing the preventative work before my long ride next week.
Don