I have a Steel City 3 h.p. shaper. I have had this machine since 2007,bought it new. Recently I noticed a vibration when I had my small rebate head in the machine and it was on the high speed.(10000) rpm. I switched to 7000 rpm and it was fine. The other day it was way worse (vibration). I proceeded to troubleshoot. I tried two different cutterheads, two spindles 1'' and 3/4'' ,ran the motor with belt off to isolate the spindle ,motor is fine. My thought is bearings need replaced. By feel they are smooth when turning the spindle by hand,no 'clicks' or roughness. No play when pulling,pushing against spindle. There is nothing else that could be causing this a AFAIK. Am I on the right track ?Anything else to look for before I pull bearings ?