Reply to VCI-100 - the acryl-ring of my left TT is mixing up pitch-bend and skipping

hey guys,
guess what. 2 weeks ago I had the biggest gig of my career and 1 hour before the show I was running a last check, when I found out, that suddenly the acrylic-ring of my left TT was changing between pitch-bend and skipping through the track. Also. the color on interaction was changing from blue to red all the time. I found out, that the left TT was much looser than the right one and that I can even pull it out a little bit. Any ideas how I can check this thing? Thanks a lot.