mill/drill motor

I have a wholesale tool version RF-30 mill/drill. I have had it for a couple of years and its always worked fine. Now when I turn the motor switch I get only a 60 Hz buzz. It will occasionally quiver and if I can hand start the spindle it will run at normal speed/power. This happens even if I take the belt off. Prior to this I was doing something and I had the switch turned only partially. I noticed that there was a buzz noise but no motor movement so I released the switch immediatly and there was no smoke or smell but I wonder if I fried something. Any help or advice would be much appreciated. Also, if it sounds like this is going to be a toasted motor I wonder if this would be a good time to consider a vfd setup as the machine is just about to be CNC'ed and the variable speed would be nice