Amazing, hell! They really knew how to build good motors back then: good steel ball or roller bearings, lots of good silicon steel in the magnetics (rotor and stator), heavy-gauge OFHC (oxygen free high conductivity) copper in the windings (probably), heavy-duty insulation on the copper, and a forged steel case to hold it all together. You buy a 1 HP, single-phase motor today and you are lucky if it lasts two years. Modern manufacturing really pushes the envelope to reduce production cost. You can pass your motor (and the 20" bandsaw it's attached to) down to your grandchildren.
You may not ever need to remove that split-pulley, but if you do, buy or rent a gear puller and soak the keyed shaft in penetrating oil overnight before attempting to remove the pulley. The penetrating oil and the overnight soak are essential. Don't try to rush it. Sometimes it helps to heat the pulley with a torch so it expands slightly.
The shaft key is sometimes wedged in so tightly that you have to try to move the pulley toward the motor face to free it. Place a steel cylinder over the end of the motor shaft and whack the pulley (not the key or the shaft!) with a leaded dead-blow hammer to move the pulley toward the motor case, away from the end of the motor shaft. Keep the whacking cylinder's outside diameter small, so the hammer impulse is transferred to the pulley, close to the shaft, nowhere near the outer edge of the pulley.
Don't "drift" the pulley too far or the the gear puller won't fit behind the pulley! However, If that works, you can then usually remove the key with a pair of locking-jaw pliers (Vice Grips) and then use the gear puller to remove the pulley from the shaft. A deep-well socket wrench that fits over the motor shaft can be handy for use as a whacker cylinder, or just use a short length of iron pipe with one end ground flat and perpendicular to the bore of the pipe. If the pulley is pot metal or cast aluminum, a rubber or leather washer should be placed over the end of the pipe to cushion the hammer blow. Have a replacement pulley on hand in case this brute force attack damages the pulley. Pulleys are cheap, motors are not. Sometimes you have to sacrifice a pulley to get it removed from the motor shaft. The keys tend to rust into place over long periods of neglect.
When you go to put the pulley back on the shaft, support the back side of the pulley with wooden blocks of appropriate thickness to position the pulley on the center-line of the drive belts. A pulley that is not centered properly will quickly wear out the belts. Once you have the pulley aligned, drive a new
key between the slotted shaft and the inner diameter of the pulley using a drift punch and a ball-peen hammer. It just needs to be snug, so tap lightly.
It probably isn't necessary to clean the inside of the motor. Just blow any dust out with low-pressure air. Maybe wipe dirt off the internal cooling fan blades if one is present. You might want to check the insulation on the individual wires of that external black cable. There is a tendency for the insulation to break down and crumble from exposure to ozone in the air. For something that old, I would replace the cable as a matter of principle with an appropriate gauge SOOW or SEOOW insulated cable