[Trombone-l] Mahler 1 mute change

[Nick Mahon]

I'm playing some excerpts from Mahler 1 for an upcoming audition.   
One excerpt from the fourth movement has a difficult mute change.   
It's right before the soft trumpet/trombone solo line.  To see the  
part I'm talking about, follow this link:

http://www.picturesinmotion.com/misc/mahler.gif

Does anyone have any tips for negotiating this mute change in an  
audition setting?  (I was considering going to the audition without a  
mute, but my teacher advised me "If it said F-flat, you'd play F- 
flat.  It says muted, so play it muted")

Thanks,
Nick Mahon