Alto Saxophone Octave/Register Key Help?

I just finished a concert today and I was in a duet with the first chair when it really start to irritate. My register key keeps sticking when coming from a note that raises it (such as an A) to a note that doesn't (G). It just delays from notes above a G when coming back down making it squeak. There's this little plastic casing on the little bar that raises the big U shaped metal piece. It's a brand new saxophone and I've only been having problems with that. So is it that little plastic piece and should I remove it? Thanks for the help~