Cutting Granite Countertop

I have a 30 year old 2 hp 20 gallon compressor that is rarely used. It has a 20 amp motor and the garage circuit is 20 amps. The first time it runs to fill the tank everything is fine, but later when it tries to start back up to refill the tank it sounds like it is running at half speed for a few seconds, then trips the circuit breaker. Resetting the breaker doesn't help. It just makes an awful electrical noise and trips. If the breaker is weak it seems like it would just trip the first time it runs so I haven't tried replacing it yet. I'm not sure what to try.

Skill 594ct3 3inch belt sander On the motor the numbers 115volts SEY 70761 Sparked and started smoking when i was using it last night, then died. Images [url=http://imgur.com/a/wEJxn]Imgur: The most awesome images on the Internet[/url] 1st picture shows the black contacts that skate along the shaft giving the motor power, one on each side. Next picture shows the black contacts connected to the wires(broken now), this is the parts i need replaced. the wires with black contacts. Others pictures you can see that its broken from the wire connectors. Was a black nub that was attached to the black pieces skating on the shaft. Original problem was the wires between the trigger and contacts was broken. WHile taking apart the motor, the old and brittle contacts just feel apart. I have no idea what the actualy name for these contacts are, or where I can even start looking for them. Its gotta be like 5cents on china stores, would greatly appreciate if someone can help me out here. Also because it was smoking, something was overheating, so how do i tell if the field or armature is damaged beyond use? so then no point getting new carbon brushes. Update: found an image online [url]http://s.hswstatic.com/gif/how-to-repair-major-appliances-8.jpg[/url] I need the carbon brush that has the nub to attach to the wires, and the new wires of course with new metal pieces. So i guess the issue is, how do I know which ones to order? size? etc