[mactec54]

Thanks. I wish the manufacturers would put colorful stickers to that effect on new spindles. Don't know how a new user should be expected to know. My old Porter Cable 7518 router mentioned in original post ran from the get go at 21,000 RPM, never required break in, and it's bearings have been going strong for some 12 years now. So I didn't expect this.

Has anyone else been able to listen to the noise in the .zip file? mactec54 has been very helpful, but I'd appreciate a second opinion from another spindle owner. While I think it's bearings, I could still be wrong on that.

Not all need the break in, quite often most just rip it to max RPM and leave it there, some do the break in, which is not always needed, if it is the bearings you should at least run it up to the max

Your Porter Cable does not have bearings like what is in these spindles, which is a completely different design.