Fadal spindle noise, help with diagnostics

Ive got a 1995 Fadal VMC 15 that ive owned for about a year now. Machine runs pretty well, however today it started making a high pitched, sort of whining noise intermittently coming from the spindle area after running at 7k RPM for the past few days. Surface finish is still good and I dont get much reading with an indicator when I push and pull on a tool in the spindle (.001-.0015), so I dont believe its a spindle bearing issue. My best guess is it is coming from the belts and pulleys. It does have some vibration or harmonics going on at higher rpms. Im assuming the teeth on the pulleys are loaded up with belt dust and coolant shmegma? I have noticed a bit of what i assume is belt dust building up near the spindle motor. Maybe the belt is rubbing somewhere?

So my question is, am I on the right track here? Is there anything else I should look for when I remove the sheet metal from the head aside from the obvious? Any tips for cleaning the pulleys? Im definitely not a machine tech so any help and insight would be greatly appreciated.

Just another game of Fix-A-Fadal

What I have noticed when the bearings start to go bad is the floor finish is the first indicator after the new noise, especially after you plunge down then face the floor of a pocket. You get "rings" from the cutter moving up and down a few millionths or tenth. I also noticed the thermal growth go from a thou or two to .006" on the 10k spindle of the 1997 Fadal I worked on when it's spindle went south, slowly. What is your max rpm?

This machine is 7500 RPM. These parts im working on have a pocket being faced with a .5 endmill and the surface finish is at least a 32, probably better, and I dont believe I have noticed any of the rings you mentioned. I do notice a few thou thermal growth in the first 30 minutes or so and it is always very consistant, about .003.