Year 2 using this. I decided to clean the entire removeable tray assembly. Took off the round tray part that has 3 legs to clean in that area. I wasn't paying attention when I took it off to put it on the same way it came off. On the round cup with 3 legs there was a 2" x 1/2 "opening near the top of it on one side only. Does that 2 " opening fit back into the Dome part on the solid side of the dome or the fence like side? Doesn't show on manual. Thanks. Karen