Tool Holder Fretting

[Daniel Odom]

I was reading an article and posts on this forum that have got me paranoid (http://www.techniksusa.com/metal/holder_maintenance.htm scroll down). I was having "popping" issues and replaced all tool holders w/ new, but am still getting faint copper rings where the tapers meet after cutting a lot of plywood. These markings are removed by ultra light grit pads but are still making me wonder if I ought to have the spindle serviced soon, before it's too late. What do you all think?