Join Date: Jan 2019
Location: Central North Carolina
It could have two types of motor. One type has brushes and you will find them under little round screw-in plastic caps on the opposite sides of the motor. Be carefull when removing them, since there is a spring behind the cap. You can remove these to check their length replace them if the length between the spring and the end is less that about 1/4 inch. Motor repair shops and better hardware stores have generic brushes, so take your's with you to match them up with what's available. Does the motor spin freely? Maybe the bearings need attention. It brush replacement and bearing lubrication doesn't solve the problem, take the motor to an electric motor repair shop for further diagnosis/repair.
In the second type of motor there are no brushes. There is a capacitor connected to the motor wiring and hidden inside the case somewhere. It is usually a round black plastic cylinder with two wires. You likely need to replace this. The physical size as well as the electrical size is important, since it won't likely fit if it isn't the same size. The electrical measurements should be printed on the side and should say something like "70 mfd 270 vac". You need to buy a replacement using the electrical measurements from the side of your capacitor as well as it's physical size. You can look for one online, or locally at an electric motor service shop, Grainger, Johnstone Supply, or other industrial supply company near you. Fastenal might have what you need too.
Now the second part of the problem. In one end, usually the non shaft end of the motor, there is a switch that opens it's contacts as the motor spins up to speed, and closes it's contacts as the motor slows down. Clean the contacts of this switch by sliding a piece of emery or crocus cloth sand paper folded in half between the switch contacts. You want to slide it back and forth to clean the oxides off the contacts to expose shiny metal on both. Be careful not to bend the switch contacts as they need to go tightly together when the sand paper is removed. Now look at the centrifugal mechanism on the motor shaft that operates this switch. There are two weights with springs that swing out as the motor spins. They slide a plastic collar on the motor shaft as they spin out moving the collar and the collar moves to open the switch. For this, you need to make certain that the surface of the motor shaft, where this collar slides, is clean and shiny, so the collar can slide freely. After cleaning, a tiny bit of light machine oil, like 3-in-one oil can be applied, but it should be a very light coating as you don't want it dripping or flying off the shaft as the motor spins.
After you replace the capacitor and clean the switch contacts and the shaft area where the collar needs to slide, put the motor back together and make certain that the motor spins freely and maybe give the bearings a little oil before testing it.