DJM 700 - Headphone Cue/ Master dial is loose, quick fix possible?

Hi,

I've had my DJM 700 since 2009 and never once had a problem with it. 

Recently, I've noticed that the headphone Cue/ Master dial has become loose. I can "wiggle" it from left to right.

It hasn't affected the sound quality, and the sound remains stable (doesn't cut out when I move it) but I fear it may eventually give up. 

Is there any quick fix I can do? I'm not sure of the layout inside the mixer, if it's just a component soldered on to a circuit board then I could maybe touch up the solder to hold it in place. I'm not sure though....

Thank you.